linux/net/xdp/xsk_queue.c
Andrew Kanner a12bbb3ccc xdp: Fix zero-size allocation warning in xskq_create()
Syzkaller reported the following issue:

  ------------[ cut here ]------------
  WARNING: CPU: 0 PID: 2807 at mm/vmalloc.c:3247 __vmalloc_node_range (mm/vmalloc.c:3361)
  Modules linked in:
  CPU: 0 PID: 2807 Comm: repro Not tainted 6.6.0-rc2+ #12
  Hardware name: Generic DT based system
  unwind_backtrace from show_stack (arch/arm/kernel/traps.c:258)
  show_stack from dump_stack_lvl (lib/dump_stack.c:107 (discriminator 1))
  dump_stack_lvl from __warn (kernel/panic.c:633 kernel/panic.c:680)
  __warn from warn_slowpath_fmt (./include/linux/context_tracking.h:153 kernel/panic.c:700)
  warn_slowpath_fmt from __vmalloc_node_range (mm/vmalloc.c:3361 (discriminator 3))
  __vmalloc_node_range from vmalloc_user (mm/vmalloc.c:3478)
  vmalloc_user from xskq_create (net/xdp/xsk_queue.c:40)
  xskq_create from xsk_setsockopt (net/xdp/xsk.c:953 net/xdp/xsk.c:1286)
  xsk_setsockopt from __sys_setsockopt (net/socket.c:2308)
  __sys_setsockopt from ret_fast_syscall (arch/arm/kernel/entry-common.S:68)

xskq_get_ring_size() uses struct_size() macro to safely calculate the
size of struct xsk_queue and q->nentries of desc members. But the
syzkaller repro was able to set q->nentries with the value initially
taken from copy_from_sockptr() high enough to return SIZE_MAX by
struct_size(). The next PAGE_ALIGN(size) is such case will overflow
the size_t value and set it to 0. This will trigger WARN_ON_ONCE in
vmalloc_user() -> __vmalloc_node_range().

The issue is reproducible on 32-bit arm kernel.

Fixes: 9f78bf330a ("xsk: support use vaddr as ring")
Reported-by: syzbot+fae676d3cf469331fc89@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/000000000000c84b4705fb31741e@google.com/T/
Reported-by: syzbot+b132693e925cbbd89e26@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/000000000000e20df20606ebab4f@google.com/T/
Signed-off-by: Andrew Kanner <andrew.kanner@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: syzbot+fae676d3cf469331fc89@syzkaller.appspotmail.com
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://syzkaller.appspot.com/bug?extid=fae676d3cf469331fc89
Link: https://lore.kernel.org/bpf/20231007075148.1759-1-andrew.kanner@gmail.com
2023-10-09 16:13:29 +02:00

67 lines
1.3 KiB
C

// SPDX-License-Identifier: GPL-2.0
/* XDP user-space ring structure
* Copyright(c) 2018 Intel Corporation.
*/
#include <linux/log2.h>
#include <linux/slab.h>
#include <linux/overflow.h>
#include <linux/vmalloc.h>
#include <net/xdp_sock_drv.h>
#include "xsk_queue.h"
static size_t xskq_get_ring_size(struct xsk_queue *q, bool umem_queue)
{
struct xdp_umem_ring *umem_ring;
struct xdp_rxtx_ring *rxtx_ring;
if (umem_queue)
return struct_size(umem_ring, desc, q->nentries);
return struct_size(rxtx_ring, desc, q->nentries);
}
struct xsk_queue *xskq_create(u32 nentries, bool umem_queue)
{
struct xsk_queue *q;
size_t size;
q = kzalloc(sizeof(*q), GFP_KERNEL);
if (!q)
return NULL;
q->nentries = nentries;
q->ring_mask = nentries - 1;
size = xskq_get_ring_size(q, umem_queue);
/* size which is overflowing or close to SIZE_MAX will become 0 in
* PAGE_ALIGN(), checking SIZE_MAX is enough due to the previous
* is_power_of_2(), the rest will be handled by vmalloc_user()
*/
if (unlikely(size == SIZE_MAX)) {
kfree(q);
return NULL;
}
size = PAGE_ALIGN(size);
q->ring = vmalloc_user(size);
if (!q->ring) {
kfree(q);
return NULL;
}
q->ring_vmalloc_size = size;
return q;
}
void xskq_destroy(struct xsk_queue *q)
{
if (!q)
return;
vfree(q->ring);
kfree(q);
}