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![Tetsuo Handa](/assets/img/avatar_default.png)
syzbot is reporting lockdep warning in __stack_depot_save(), for the caller of __stack_depot_save() (i.e. __kasan_record_aux_stack() in this report) is responsible for masking __GFP_KSWAPD_RECLAIM flag in order not to wake kswapd which in turn wakes kcompactd. Since kasan/kmsan functions might be called with arbitrary locks held, mask __GFP_KSWAPD_RECLAIM flag from all GFP_NOWAIT/GFP_ATOMIC allocations in kasan/kmsan. Note that kmsan_save_stack_with_flags() is changed to mask both __GFP_DIRECT_RECLAIM flag and __GFP_KSWAPD_RECLAIM flag, for wakeup_kswapd() from wake_all_kswapds() from __alloc_pages_slowpath() calls wakeup_kcompactd() if __GFP_KSWAPD_RECLAIM flag is set and __GFP_DIRECT_RECLAIM flag is not set. Link: https://lkml.kernel.org/r/656cb4f5-998b-c8d7-3c61-c2d37aa90f9a@I-love.SAKURA.ne.jp Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: syzbot <syzbot+ece2915262061d6e0ac1@syzkaller.appspotmail.com> Closes: https://syzkaller.appspot.com/bug?extid=ece2915262061d6e0ac1 Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Alexander Potapenko <glider@google.com> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Marco Elver <elver@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
455 lines
13 KiB
C
455 lines
13 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* KMSAN runtime library.
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*
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* Copyright (C) 2017-2022 Google LLC
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* Author: Alexander Potapenko <glider@google.com>
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*
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*/
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#include <asm/page.h>
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#include <linux/compiler.h>
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#include <linux/export.h>
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#include <linux/highmem.h>
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#include <linux/interrupt.h>
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#include <linux/kernel.h>
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#include <linux/kmsan_types.h>
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#include <linux/memory.h>
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#include <linux/mm.h>
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#include <linux/mm_types.h>
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#include <linux/mmzone.h>
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#include <linux/percpu-defs.h>
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#include <linux/preempt.h>
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#include <linux/slab.h>
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#include <linux/stackdepot.h>
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#include <linux/stacktrace.h>
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#include <linux/types.h>
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#include <linux/vmalloc.h>
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#include "../slab.h"
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#include "kmsan.h"
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bool kmsan_enabled __read_mostly;
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/*
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* Per-CPU KMSAN context to be used in interrupts, where current->kmsan is
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* unavaliable.
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*/
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DEFINE_PER_CPU(struct kmsan_ctx, kmsan_percpu_ctx);
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void kmsan_internal_task_create(struct task_struct *task)
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{
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struct kmsan_ctx *ctx = &task->kmsan_ctx;
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struct thread_info *info = current_thread_info();
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__memset(ctx, 0, sizeof(*ctx));
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ctx->allow_reporting = true;
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kmsan_internal_unpoison_memory(info, sizeof(*info), false);
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}
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void kmsan_internal_poison_memory(void *address, size_t size, gfp_t flags,
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unsigned int poison_flags)
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{
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u32 extra_bits =
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kmsan_extra_bits(/*depth*/ 0, poison_flags & KMSAN_POISON_FREE);
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bool checked = poison_flags & KMSAN_POISON_CHECK;
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depot_stack_handle_t handle;
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handle = kmsan_save_stack_with_flags(flags, extra_bits);
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kmsan_internal_set_shadow_origin(address, size, -1, handle, checked);
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}
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void kmsan_internal_unpoison_memory(void *address, size_t size, bool checked)
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{
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kmsan_internal_set_shadow_origin(address, size, 0, 0, checked);
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}
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depot_stack_handle_t kmsan_save_stack_with_flags(gfp_t flags,
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unsigned int extra)
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{
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unsigned long entries[KMSAN_STACK_DEPTH];
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unsigned int nr_entries;
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depot_stack_handle_t handle;
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nr_entries = stack_trace_save(entries, KMSAN_STACK_DEPTH, 0);
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/* Don't sleep. */
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flags &= ~(__GFP_DIRECT_RECLAIM | __GFP_KSWAPD_RECLAIM);
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handle = __stack_depot_save(entries, nr_entries, flags, true);
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return stack_depot_set_extra_bits(handle, extra);
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}
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/* Copy the metadata following the memmove() behavior. */
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void kmsan_internal_memmove_metadata(void *dst, void *src, size_t n)
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{
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depot_stack_handle_t old_origin = 0, new_origin = 0;
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int src_slots, dst_slots, i, iter, step, skip_bits;
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depot_stack_handle_t *origin_src, *origin_dst;
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void *shadow_src, *shadow_dst;
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u32 *align_shadow_src, shadow;
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bool backwards;
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shadow_dst = kmsan_get_metadata(dst, KMSAN_META_SHADOW);
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if (!shadow_dst)
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return;
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KMSAN_WARN_ON(!kmsan_metadata_is_contiguous(dst, n));
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shadow_src = kmsan_get_metadata(src, KMSAN_META_SHADOW);
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if (!shadow_src) {
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/*
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* @src is untracked: zero out destination shadow, ignore the
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* origins, we're done.
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*/
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__memset(shadow_dst, 0, n);
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return;
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}
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KMSAN_WARN_ON(!kmsan_metadata_is_contiguous(src, n));
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__memmove(shadow_dst, shadow_src, n);
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origin_dst = kmsan_get_metadata(dst, KMSAN_META_ORIGIN);
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origin_src = kmsan_get_metadata(src, KMSAN_META_ORIGIN);
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KMSAN_WARN_ON(!origin_dst || !origin_src);
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src_slots = (ALIGN((u64)src + n, KMSAN_ORIGIN_SIZE) -
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ALIGN_DOWN((u64)src, KMSAN_ORIGIN_SIZE)) /
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KMSAN_ORIGIN_SIZE;
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dst_slots = (ALIGN((u64)dst + n, KMSAN_ORIGIN_SIZE) -
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ALIGN_DOWN((u64)dst, KMSAN_ORIGIN_SIZE)) /
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KMSAN_ORIGIN_SIZE;
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KMSAN_WARN_ON((src_slots < 1) || (dst_slots < 1));
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KMSAN_WARN_ON((src_slots - dst_slots > 1) ||
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(dst_slots - src_slots < -1));
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backwards = dst > src;
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i = backwards ? min(src_slots, dst_slots) - 1 : 0;
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iter = backwards ? -1 : 1;
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align_shadow_src =
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(u32 *)ALIGN_DOWN((u64)shadow_src, KMSAN_ORIGIN_SIZE);
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for (step = 0; step < min(src_slots, dst_slots); step++, i += iter) {
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KMSAN_WARN_ON(i < 0);
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shadow = align_shadow_src[i];
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if (i == 0) {
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/*
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* If @src isn't aligned on KMSAN_ORIGIN_SIZE, don't
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* look at the first @src % KMSAN_ORIGIN_SIZE bytes
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* of the first shadow slot.
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*/
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skip_bits = ((u64)src % KMSAN_ORIGIN_SIZE) * 8;
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shadow = (shadow >> skip_bits) << skip_bits;
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}
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if (i == src_slots - 1) {
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/*
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* If @src + n isn't aligned on
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* KMSAN_ORIGIN_SIZE, don't look at the last
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* (@src + n) % KMSAN_ORIGIN_SIZE bytes of the
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* last shadow slot.
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*/
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skip_bits = (((u64)src + n) % KMSAN_ORIGIN_SIZE) * 8;
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shadow = (shadow << skip_bits) >> skip_bits;
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}
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/*
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* Overwrite the origin only if the corresponding
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* shadow is nonempty.
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*/
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if (origin_src[i] && (origin_src[i] != old_origin) && shadow) {
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old_origin = origin_src[i];
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new_origin = kmsan_internal_chain_origin(old_origin);
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/*
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* kmsan_internal_chain_origin() may return
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* NULL, but we don't want to lose the previous
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* origin value.
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*/
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if (!new_origin)
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new_origin = old_origin;
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}
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if (shadow)
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origin_dst[i] = new_origin;
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else
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origin_dst[i] = 0;
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}
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/*
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* If dst_slots is greater than src_slots (i.e.
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* dst_slots == src_slots + 1), there is an extra origin slot at the
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* beginning or end of the destination buffer, for which we take the
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* origin from the previous slot.
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* This is only done if the part of the source shadow corresponding to
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* slot is non-zero.
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*
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* E.g. if we copy 8 aligned bytes that are marked as uninitialized
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* and have origins o111 and o222, to an unaligned buffer with offset 1,
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* these two origins are copied to three origin slots, so one of then
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* needs to be duplicated, depending on the copy direction (@backwards)
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*
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* src shadow: |uuuu|uuuu|....|
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* src origin: |o111|o222|....|
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*
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* backwards = 0:
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* dst shadow: |.uuu|uuuu|u...|
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* dst origin: |....|o111|o222| - fill the empty slot with o111
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* backwards = 1:
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* dst shadow: |.uuu|uuuu|u...|
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* dst origin: |o111|o222|....| - fill the empty slot with o222
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*/
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if (src_slots < dst_slots) {
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if (backwards) {
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shadow = align_shadow_src[src_slots - 1];
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skip_bits = (((u64)dst + n) % KMSAN_ORIGIN_SIZE) * 8;
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shadow = (shadow << skip_bits) >> skip_bits;
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if (shadow)
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/* src_slots > 0, therefore dst_slots is at least 2 */
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origin_dst[dst_slots - 1] =
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origin_dst[dst_slots - 2];
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} else {
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shadow = align_shadow_src[0];
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skip_bits = ((u64)dst % KMSAN_ORIGIN_SIZE) * 8;
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shadow = (shadow >> skip_bits) << skip_bits;
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if (shadow)
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origin_dst[0] = origin_dst[1];
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}
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}
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}
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depot_stack_handle_t kmsan_internal_chain_origin(depot_stack_handle_t id)
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{
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unsigned long entries[3];
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u32 extra_bits;
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int depth;
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bool uaf;
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depot_stack_handle_t handle;
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if (!id)
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return id;
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/*
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* Make sure we have enough spare bits in @id to hold the UAF bit and
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* the chain depth.
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*/
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BUILD_BUG_ON(
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(1 << STACK_DEPOT_EXTRA_BITS) <= (KMSAN_MAX_ORIGIN_DEPTH << 1));
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extra_bits = stack_depot_get_extra_bits(id);
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depth = kmsan_depth_from_eb(extra_bits);
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uaf = kmsan_uaf_from_eb(extra_bits);
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/*
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* Stop chaining origins once the depth reached KMSAN_MAX_ORIGIN_DEPTH.
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* This mostly happens in the case structures with uninitialized padding
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* are copied around many times. Origin chains for such structures are
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* usually periodic, and it does not make sense to fully store them.
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*/
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if (depth == KMSAN_MAX_ORIGIN_DEPTH)
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return id;
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depth++;
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extra_bits = kmsan_extra_bits(depth, uaf);
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entries[0] = KMSAN_CHAIN_MAGIC_ORIGIN;
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entries[1] = kmsan_save_stack_with_flags(__GFP_HIGH, 0);
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entries[2] = id;
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/*
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* @entries is a local var in non-instrumented code, so KMSAN does not
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* know it is initialized. Explicitly unpoison it to avoid false
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* positives when __stack_depot_save() passes it to instrumented code.
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*/
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kmsan_internal_unpoison_memory(entries, sizeof(entries), false);
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handle = __stack_depot_save(entries, ARRAY_SIZE(entries), __GFP_HIGH,
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true);
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return stack_depot_set_extra_bits(handle, extra_bits);
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}
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void kmsan_internal_set_shadow_origin(void *addr, size_t size, int b,
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u32 origin, bool checked)
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{
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u64 address = (u64)addr;
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void *shadow_start;
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u32 *origin_start;
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size_t pad = 0;
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KMSAN_WARN_ON(!kmsan_metadata_is_contiguous(addr, size));
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shadow_start = kmsan_get_metadata(addr, KMSAN_META_SHADOW);
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if (!shadow_start) {
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/*
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* kmsan_metadata_is_contiguous() is true, so either all shadow
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* and origin pages are NULL, or all are non-NULL.
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*/
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if (checked) {
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pr_err("%s: not memsetting %ld bytes starting at %px, because the shadow is NULL\n",
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__func__, size, addr);
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KMSAN_WARN_ON(true);
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}
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return;
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}
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__memset(shadow_start, b, size);
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if (!IS_ALIGNED(address, KMSAN_ORIGIN_SIZE)) {
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pad = address % KMSAN_ORIGIN_SIZE;
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address -= pad;
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size += pad;
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}
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size = ALIGN(size, KMSAN_ORIGIN_SIZE);
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origin_start =
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(u32 *)kmsan_get_metadata((void *)address, KMSAN_META_ORIGIN);
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for (int i = 0; i < size / KMSAN_ORIGIN_SIZE; i++)
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origin_start[i] = origin;
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}
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struct page *kmsan_vmalloc_to_page_or_null(void *vaddr)
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{
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struct page *page;
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if (!kmsan_internal_is_vmalloc_addr(vaddr) &&
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!kmsan_internal_is_module_addr(vaddr))
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return NULL;
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page = vmalloc_to_page(vaddr);
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if (pfn_valid(page_to_pfn(page)))
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return page;
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else
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return NULL;
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}
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void kmsan_internal_check_memory(void *addr, size_t size, const void *user_addr,
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int reason)
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{
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depot_stack_handle_t cur_origin = 0, new_origin = 0;
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unsigned long addr64 = (unsigned long)addr;
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depot_stack_handle_t *origin = NULL;
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unsigned char *shadow = NULL;
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int cur_off_start = -1;
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int chunk_size;
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size_t pos = 0;
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if (!size)
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return;
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KMSAN_WARN_ON(!kmsan_metadata_is_contiguous(addr, size));
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while (pos < size) {
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chunk_size = min(size - pos,
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PAGE_SIZE - ((addr64 + pos) % PAGE_SIZE));
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shadow = kmsan_get_metadata((void *)(addr64 + pos),
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KMSAN_META_SHADOW);
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if (!shadow) {
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/*
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* This page is untracked. If there were uninitialized
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* bytes before, report them.
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*/
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if (cur_origin) {
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kmsan_enter_runtime();
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kmsan_report(cur_origin, addr, size,
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cur_off_start, pos - 1, user_addr,
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reason);
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kmsan_leave_runtime();
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}
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cur_origin = 0;
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cur_off_start = -1;
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pos += chunk_size;
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continue;
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}
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for (int i = 0; i < chunk_size; i++) {
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if (!shadow[i]) {
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/*
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* This byte is unpoisoned. If there were
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* poisoned bytes before, report them.
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*/
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if (cur_origin) {
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kmsan_enter_runtime();
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kmsan_report(cur_origin, addr, size,
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cur_off_start, pos + i - 1,
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user_addr, reason);
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kmsan_leave_runtime();
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}
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cur_origin = 0;
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cur_off_start = -1;
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continue;
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}
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origin = kmsan_get_metadata((void *)(addr64 + pos + i),
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KMSAN_META_ORIGIN);
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KMSAN_WARN_ON(!origin);
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new_origin = *origin;
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/*
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* Encountered new origin - report the previous
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* uninitialized range.
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*/
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if (cur_origin != new_origin) {
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if (cur_origin) {
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kmsan_enter_runtime();
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kmsan_report(cur_origin, addr, size,
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cur_off_start, pos + i - 1,
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user_addr, reason);
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kmsan_leave_runtime();
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}
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cur_origin = new_origin;
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cur_off_start = pos + i;
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}
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}
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pos += chunk_size;
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}
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KMSAN_WARN_ON(pos != size);
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if (cur_origin) {
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kmsan_enter_runtime();
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kmsan_report(cur_origin, addr, size, cur_off_start, pos - 1,
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user_addr, reason);
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kmsan_leave_runtime();
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}
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}
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bool kmsan_metadata_is_contiguous(void *addr, size_t size)
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{
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char *cur_shadow = NULL, *next_shadow = NULL, *cur_origin = NULL,
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*next_origin = NULL;
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u64 cur_addr = (u64)addr, next_addr = cur_addr + PAGE_SIZE;
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depot_stack_handle_t *origin_p;
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bool all_untracked = false;
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if (!size)
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return true;
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/* The whole range belongs to the same page. */
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if (ALIGN_DOWN(cur_addr + size - 1, PAGE_SIZE) ==
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ALIGN_DOWN(cur_addr, PAGE_SIZE))
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return true;
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cur_shadow = kmsan_get_metadata((void *)cur_addr, /*is_origin*/ false);
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if (!cur_shadow)
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all_untracked = true;
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cur_origin = kmsan_get_metadata((void *)cur_addr, /*is_origin*/ true);
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if (all_untracked && cur_origin)
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goto report;
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for (; next_addr < (u64)addr + size;
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cur_addr = next_addr, cur_shadow = next_shadow,
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cur_origin = next_origin, next_addr += PAGE_SIZE) {
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next_shadow = kmsan_get_metadata((void *)next_addr, false);
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next_origin = kmsan_get_metadata((void *)next_addr, true);
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if (all_untracked) {
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if (next_shadow || next_origin)
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goto report;
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if (!next_shadow && !next_origin)
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continue;
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}
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if (((u64)cur_shadow == ((u64)next_shadow - PAGE_SIZE)) &&
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((u64)cur_origin == ((u64)next_origin - PAGE_SIZE)))
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continue;
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goto report;
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}
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return true;
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|
|
report:
|
|
pr_err("%s: attempting to access two shadow page ranges.\n", __func__);
|
|
pr_err("Access of size %ld at %px.\n", size, addr);
|
|
pr_err("Addresses belonging to different ranges: %px and %px\n",
|
|
(void *)cur_addr, (void *)next_addr);
|
|
pr_err("page[0].shadow: %px, page[1].shadow: %px\n", cur_shadow,
|
|
next_shadow);
|
|
pr_err("page[0].origin: %px, page[1].origin: %px\n", cur_origin,
|
|
next_origin);
|
|
origin_p = kmsan_get_metadata(addr, KMSAN_META_ORIGIN);
|
|
if (origin_p) {
|
|
pr_err("Origin: %08x\n", *origin_p);
|
|
kmsan_print_origin(*origin_p);
|
|
} else {
|
|
pr_err("Origin: unavailable\n");
|
|
}
|
|
return false;
|
|
}
|