linux/kernel/crash_core.c
Stephen Brennan 08fc35f31b vmcoreinfo: warn if we exceed vmcoreinfo data size
Though vmcoreinfo is intended to be small, at just one page, useful
information is still added to it, so we risk running out of space. 
Currently there is no runtime check to see whether the vmcoreinfo buffer
has been exhausted.  Add a warning for this case.

Currently, my static checking tool[1] indicates that a good upper bound
for vmcoreinfo size is currently 3415 bytes, but the best time to add
warnings is before the risk becomes too high.

[1] https://github.com/brenns10/kernel_stuff/blob/master/vmcoreinfosize/vmcoreinfosize.py

Link: https://lkml.kernel.org/r/20221027205008.312534-1-stephen.s.brennan@oracle.com
Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-11-30 16:13:17 -08:00

518 lines
13 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* crash.c - kernel crash support code.
* Copyright (C) 2002-2004 Eric Biederman <ebiederm@xmission.com>
*/
#include <linux/buildid.h>
#include <linux/crash_core.h>
#include <linux/init.h>
#include <linux/utsname.h>
#include <linux/vmalloc.h>
#include <linux/sizes.h>
#include <asm/page.h>
#include <asm/sections.h>
#include <crypto/sha1.h>
#include "kallsyms_internal.h"
/* vmcoreinfo stuff */
unsigned char *vmcoreinfo_data;
size_t vmcoreinfo_size;
u32 *vmcoreinfo_note;
/* trusted vmcoreinfo, e.g. we can make a copy in the crash memory */
static unsigned char *vmcoreinfo_data_safecopy;
/*
* parsing the "crashkernel" commandline
*
* this code is intended to be called from architecture specific code
*/
/*
* This function parses command lines in the format
*
* crashkernel=ramsize-range:size[,...][@offset]
*
* The function returns 0 on success and -EINVAL on failure.
*/
static int __init parse_crashkernel_mem(char *cmdline,
unsigned long long system_ram,
unsigned long long *crash_size,
unsigned long long *crash_base)
{
char *cur = cmdline, *tmp;
unsigned long long total_mem = system_ram;
/*
* Firmware sometimes reserves some memory regions for its own use,
* so the system memory size is less than the actual physical memory
* size. Work around this by rounding up the total size to 128M,
* which is enough for most test cases.
*/
total_mem = roundup(total_mem, SZ_128M);
/* for each entry of the comma-separated list */
do {
unsigned long long start, end = ULLONG_MAX, size;
/* get the start of the range */
start = memparse(cur, &tmp);
if (cur == tmp) {
pr_warn("crashkernel: Memory value expected\n");
return -EINVAL;
}
cur = tmp;
if (*cur != '-') {
pr_warn("crashkernel: '-' expected\n");
return -EINVAL;
}
cur++;
/* if no ':' is here, than we read the end */
if (*cur != ':') {
end = memparse(cur, &tmp);
if (cur == tmp) {
pr_warn("crashkernel: Memory value expected\n");
return -EINVAL;
}
cur = tmp;
if (end <= start) {
pr_warn("crashkernel: end <= start\n");
return -EINVAL;
}
}
if (*cur != ':') {
pr_warn("crashkernel: ':' expected\n");
return -EINVAL;
}
cur++;
size = memparse(cur, &tmp);
if (cur == tmp) {
pr_warn("Memory value expected\n");
return -EINVAL;
}
cur = tmp;
if (size >= total_mem) {
pr_warn("crashkernel: invalid size\n");
return -EINVAL;
}
/* match ? */
if (total_mem >= start && total_mem < end) {
*crash_size = size;
break;
}
} while (*cur++ == ',');
if (*crash_size > 0) {
while (*cur && *cur != ' ' && *cur != '@')
cur++;
if (*cur == '@') {
cur++;
*crash_base = memparse(cur, &tmp);
if (cur == tmp) {
pr_warn("Memory value expected after '@'\n");
return -EINVAL;
}
}
} else
pr_info("crashkernel size resulted in zero bytes\n");
return 0;
}
/*
* That function parses "simple" (old) crashkernel command lines like
*
* crashkernel=size[@offset]
*
* It returns 0 on success and -EINVAL on failure.
*/
static int __init parse_crashkernel_simple(char *cmdline,
unsigned long long *crash_size,
unsigned long long *crash_base)
{
char *cur = cmdline;
*crash_size = memparse(cmdline, &cur);
if (cmdline == cur) {
pr_warn("crashkernel: memory value expected\n");
return -EINVAL;
}
if (*cur == '@')
*crash_base = memparse(cur+1, &cur);
else if (*cur != ' ' && *cur != '\0') {
pr_warn("crashkernel: unrecognized char: %c\n", *cur);
return -EINVAL;
}
return 0;
}
#define SUFFIX_HIGH 0
#define SUFFIX_LOW 1
#define SUFFIX_NULL 2
static __initdata char *suffix_tbl[] = {
[SUFFIX_HIGH] = ",high",
[SUFFIX_LOW] = ",low",
[SUFFIX_NULL] = NULL,
};
/*
* That function parses "suffix" crashkernel command lines like
*
* crashkernel=size,[high|low]
*
* It returns 0 on success and -EINVAL on failure.
*/
static int __init parse_crashkernel_suffix(char *cmdline,
unsigned long long *crash_size,
const char *suffix)
{
char *cur = cmdline;
*crash_size = memparse(cmdline, &cur);
if (cmdline == cur) {
pr_warn("crashkernel: memory value expected\n");
return -EINVAL;
}
/* check with suffix */
if (strncmp(cur, suffix, strlen(suffix))) {
pr_warn("crashkernel: unrecognized char: %c\n", *cur);
return -EINVAL;
}
cur += strlen(suffix);
if (*cur != ' ' && *cur != '\0') {
pr_warn("crashkernel: unrecognized char: %c\n", *cur);
return -EINVAL;
}
return 0;
}
static __init char *get_last_crashkernel(char *cmdline,
const char *name,
const char *suffix)
{
char *p = cmdline, *ck_cmdline = NULL;
/* find crashkernel and use the last one if there are more */
p = strstr(p, name);
while (p) {
char *end_p = strchr(p, ' ');
char *q;
if (!end_p)
end_p = p + strlen(p);
if (!suffix) {
int i;
/* skip the one with any known suffix */
for (i = 0; suffix_tbl[i]; i++) {
q = end_p - strlen(suffix_tbl[i]);
if (!strncmp(q, suffix_tbl[i],
strlen(suffix_tbl[i])))
goto next;
}
ck_cmdline = p;
} else {
q = end_p - strlen(suffix);
if (!strncmp(q, suffix, strlen(suffix)))
ck_cmdline = p;
}
next:
p = strstr(p+1, name);
}
return ck_cmdline;
}
static int __init __parse_crashkernel(char *cmdline,
unsigned long long system_ram,
unsigned long long *crash_size,
unsigned long long *crash_base,
const char *name,
const char *suffix)
{
char *first_colon, *first_space;
char *ck_cmdline;
BUG_ON(!crash_size || !crash_base);
*crash_size = 0;
*crash_base = 0;
ck_cmdline = get_last_crashkernel(cmdline, name, suffix);
if (!ck_cmdline)
return -ENOENT;
ck_cmdline += strlen(name);
if (suffix)
return parse_crashkernel_suffix(ck_cmdline, crash_size,
suffix);
/*
* if the commandline contains a ':', then that's the extended
* syntax -- if not, it must be the classic syntax
*/
first_colon = strchr(ck_cmdline, ':');
first_space = strchr(ck_cmdline, ' ');
if (first_colon && (!first_space || first_colon < first_space))
return parse_crashkernel_mem(ck_cmdline, system_ram,
crash_size, crash_base);
return parse_crashkernel_simple(ck_cmdline, crash_size, crash_base);
}
/*
* That function is the entry point for command line parsing and should be
* called from the arch-specific code.
*/
int __init parse_crashkernel(char *cmdline,
unsigned long long system_ram,
unsigned long long *crash_size,
unsigned long long *crash_base)
{
return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
"crashkernel=", NULL);
}
int __init parse_crashkernel_high(char *cmdline,
unsigned long long system_ram,
unsigned long long *crash_size,
unsigned long long *crash_base)
{
return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
"crashkernel=", suffix_tbl[SUFFIX_HIGH]);
}
int __init parse_crashkernel_low(char *cmdline,
unsigned long long system_ram,
unsigned long long *crash_size,
unsigned long long *crash_base)
{
return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
"crashkernel=", suffix_tbl[SUFFIX_LOW]);
}
/*
* Add a dummy early_param handler to mark crashkernel= as a known command line
* parameter and suppress incorrect warnings in init/main.c.
*/
static int __init parse_crashkernel_dummy(char *arg)
{
return 0;
}
early_param("crashkernel", parse_crashkernel_dummy);
Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
void *data, size_t data_len)
{
struct elf_note *note = (struct elf_note *)buf;
note->n_namesz = strlen(name) + 1;
note->n_descsz = data_len;
note->n_type = type;
buf += DIV_ROUND_UP(sizeof(*note), sizeof(Elf_Word));
memcpy(buf, name, note->n_namesz);
buf += DIV_ROUND_UP(note->n_namesz, sizeof(Elf_Word));
memcpy(buf, data, data_len);
buf += DIV_ROUND_UP(data_len, sizeof(Elf_Word));
return buf;
}
void final_note(Elf_Word *buf)
{
memset(buf, 0, sizeof(struct elf_note));
}
static void update_vmcoreinfo_note(void)
{
u32 *buf = vmcoreinfo_note;
if (!vmcoreinfo_size)
return;
buf = append_elf_note(buf, VMCOREINFO_NOTE_NAME, 0, vmcoreinfo_data,
vmcoreinfo_size);
final_note(buf);
}
void crash_update_vmcoreinfo_safecopy(void *ptr)
{
if (ptr)
memcpy(ptr, vmcoreinfo_data, vmcoreinfo_size);
vmcoreinfo_data_safecopy = ptr;
}
void crash_save_vmcoreinfo(void)
{
if (!vmcoreinfo_note)
return;
/* Use the safe copy to generate vmcoreinfo note if have */
if (vmcoreinfo_data_safecopy)
vmcoreinfo_data = vmcoreinfo_data_safecopy;
vmcoreinfo_append_str("CRASHTIME=%lld\n", ktime_get_real_seconds());
update_vmcoreinfo_note();
}
void vmcoreinfo_append_str(const char *fmt, ...)
{
va_list args;
char buf[0x50];
size_t r;
va_start(args, fmt);
r = vscnprintf(buf, sizeof(buf), fmt, args);
va_end(args);
r = min(r, (size_t)VMCOREINFO_BYTES - vmcoreinfo_size);
memcpy(&vmcoreinfo_data[vmcoreinfo_size], buf, r);
vmcoreinfo_size += r;
WARN_ONCE(vmcoreinfo_size == VMCOREINFO_BYTES,
"vmcoreinfo data exceeds allocated size, truncating");
}
/*
* provide an empty default implementation here -- architecture
* code may override this
*/
void __weak arch_crash_save_vmcoreinfo(void)
{}
phys_addr_t __weak paddr_vmcoreinfo_note(void)
{
return __pa(vmcoreinfo_note);
}
EXPORT_SYMBOL(paddr_vmcoreinfo_note);
static int __init crash_save_vmcoreinfo_init(void)
{
vmcoreinfo_data = (unsigned char *)get_zeroed_page(GFP_KERNEL);
if (!vmcoreinfo_data) {
pr_warn("Memory allocation for vmcoreinfo_data failed\n");
return -ENOMEM;
}
vmcoreinfo_note = alloc_pages_exact(VMCOREINFO_NOTE_SIZE,
GFP_KERNEL | __GFP_ZERO);
if (!vmcoreinfo_note) {
free_page((unsigned long)vmcoreinfo_data);
vmcoreinfo_data = NULL;
pr_warn("Memory allocation for vmcoreinfo_note failed\n");
return -ENOMEM;
}
VMCOREINFO_OSRELEASE(init_uts_ns.name.release);
VMCOREINFO_BUILD_ID();
VMCOREINFO_PAGESIZE(PAGE_SIZE);
VMCOREINFO_SYMBOL(init_uts_ns);
VMCOREINFO_OFFSET(uts_namespace, name);
VMCOREINFO_SYMBOL(node_online_map);
#ifdef CONFIG_MMU
VMCOREINFO_SYMBOL_ARRAY(swapper_pg_dir);
#endif
VMCOREINFO_SYMBOL(_stext);
VMCOREINFO_SYMBOL(vmap_area_list);
#ifndef CONFIG_NUMA
VMCOREINFO_SYMBOL(mem_map);
VMCOREINFO_SYMBOL(contig_page_data);
#endif
#ifdef CONFIG_SPARSEMEM
VMCOREINFO_SYMBOL_ARRAY(mem_section);
VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS);
VMCOREINFO_STRUCT_SIZE(mem_section);
VMCOREINFO_OFFSET(mem_section, section_mem_map);
VMCOREINFO_NUMBER(SECTION_SIZE_BITS);
VMCOREINFO_NUMBER(MAX_PHYSMEM_BITS);
#endif
VMCOREINFO_STRUCT_SIZE(page);
VMCOREINFO_STRUCT_SIZE(pglist_data);
VMCOREINFO_STRUCT_SIZE(zone);
VMCOREINFO_STRUCT_SIZE(free_area);
VMCOREINFO_STRUCT_SIZE(list_head);
VMCOREINFO_SIZE(nodemask_t);
VMCOREINFO_OFFSET(page, flags);
VMCOREINFO_OFFSET(page, _refcount);
VMCOREINFO_OFFSET(page, mapping);
VMCOREINFO_OFFSET(page, lru);
VMCOREINFO_OFFSET(page, _mapcount);
VMCOREINFO_OFFSET(page, private);
VMCOREINFO_OFFSET(page, compound_dtor);
VMCOREINFO_OFFSET(page, compound_order);
VMCOREINFO_OFFSET(page, compound_head);
VMCOREINFO_OFFSET(pglist_data, node_zones);
VMCOREINFO_OFFSET(pglist_data, nr_zones);
#ifdef CONFIG_FLATMEM
VMCOREINFO_OFFSET(pglist_data, node_mem_map);
#endif
VMCOREINFO_OFFSET(pglist_data, node_start_pfn);
VMCOREINFO_OFFSET(pglist_data, node_spanned_pages);
VMCOREINFO_OFFSET(pglist_data, node_id);
VMCOREINFO_OFFSET(zone, free_area);
VMCOREINFO_OFFSET(zone, vm_stat);
VMCOREINFO_OFFSET(zone, spanned_pages);
VMCOREINFO_OFFSET(free_area, free_list);
VMCOREINFO_OFFSET(list_head, next);
VMCOREINFO_OFFSET(list_head, prev);
VMCOREINFO_OFFSET(vmap_area, va_start);
VMCOREINFO_OFFSET(vmap_area, list);
VMCOREINFO_LENGTH(zone.free_area, MAX_ORDER);
log_buf_vmcoreinfo_setup();
VMCOREINFO_LENGTH(free_area.free_list, MIGRATE_TYPES);
VMCOREINFO_NUMBER(NR_FREE_PAGES);
VMCOREINFO_NUMBER(PG_lru);
VMCOREINFO_NUMBER(PG_private);
VMCOREINFO_NUMBER(PG_swapcache);
VMCOREINFO_NUMBER(PG_swapbacked);
VMCOREINFO_NUMBER(PG_slab);
#ifdef CONFIG_MEMORY_FAILURE
VMCOREINFO_NUMBER(PG_hwpoison);
#endif
VMCOREINFO_NUMBER(PG_head_mask);
#define PAGE_BUDDY_MAPCOUNT_VALUE (~PG_buddy)
VMCOREINFO_NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE);
#ifdef CONFIG_HUGETLB_PAGE
VMCOREINFO_NUMBER(HUGETLB_PAGE_DTOR);
#define PAGE_OFFLINE_MAPCOUNT_VALUE (~PG_offline)
VMCOREINFO_NUMBER(PAGE_OFFLINE_MAPCOUNT_VALUE);
#endif
#ifdef CONFIG_KALLSYMS
VMCOREINFO_SYMBOL(kallsyms_names);
VMCOREINFO_SYMBOL(kallsyms_num_syms);
VMCOREINFO_SYMBOL(kallsyms_token_table);
VMCOREINFO_SYMBOL(kallsyms_token_index);
#ifdef CONFIG_KALLSYMS_BASE_RELATIVE
VMCOREINFO_SYMBOL(kallsyms_offsets);
VMCOREINFO_SYMBOL(kallsyms_relative_base);
#else
VMCOREINFO_SYMBOL(kallsyms_addresses);
#endif /* CONFIG_KALLSYMS_BASE_RELATIVE */
#endif /* CONFIG_KALLSYMS */
arch_crash_save_vmcoreinfo();
update_vmcoreinfo_note();
return 0;
}
subsys_initcall(crash_save_vmcoreinfo_init);