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pstore: Change kmsg_bytes storage size to u32

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The types around kmsg_bytes were inconsistent. The global was unsigned
long, the argument to pstore_set_kmsg_bytes() was int, and the filesystem
option was u32. Given other internal limits, there's not much sense
in making a single pstore record larger than INT_MAX and it can't be
negative, so use u32 everywhere. Additionally, use READ/WRITE_ONCE and a
local variable in pstore_dump() to avoid kmsg_bytes changing during a
dump.

Link: https://lore.kernel.org/r/20250206191655.work.798-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
This commit is contained in:
Kees Cook 2025-02-06 11:16:59 -08:00
parent a64dcfb451
commit 5674609535
3 changed files with 9 additions and 8 deletions
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2
fs/pstore/inode.c
View File

@ -265,7 +265,7 @@ static void parse_options(char *options)
static int pstore_show_options(struct seq_file *m, struct dentry *root)
{
if (kmsg_bytes != CONFIG_PSTORE_DEFAULT_KMSG_BYTES)
seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes);
seq_printf(m, ",kmsg_bytes=%u", kmsg_bytes);
return 0;
}

4
fs/pstore/internal.h
View File

@ -6,7 +6,7 @@
#include <linux/time.h>
#include <linux/pstore.h>
extern unsigned long kmsg_bytes;
extern unsigned int kmsg_bytes;
#ifdef CONFIG_PSTORE_FTRACE
extern void pstore_register_ftrace(void);
@ -35,7 +35,7 @@ static inline void pstore_unregister_pmsg(void) {}
extern struct pstore_info *psinfo;
extern void pstore_set_kmsg_bytes(int);
extern void pstore_set_kmsg_bytes(unsigned int bytes);
extern void pstore_get_records(int);
extern void pstore_get_backend_records(struct pstore_info *psi,
struct dentry *root, int quiet);

11
fs/pstore/platform.c
View File

@ -92,8 +92,8 @@ module_param(compress, charp, 0444);
MODULE_PARM_DESC(compress, "compression to use");
/* How much of the kernel log to snapshot */
unsigned long kmsg_bytes = CONFIG_PSTORE_DEFAULT_KMSG_BYTES;
module_param(kmsg_bytes, ulong, 0444);
unsigned int kmsg_bytes = CONFIG_PSTORE_DEFAULT_KMSG_BYTES;
module_param(kmsg_bytes, uint, 0444);
MODULE_PARM_DESC(kmsg_bytes, "amount of kernel log to snapshot (in bytes)");
static void *compress_workspace;
@ -107,9 +107,9 @@ static void *compress_workspace;
static char *big_oops_buf;
static size_t max_compressed_size;
void pstore_set_kmsg_bytes(int bytes)
void pstore_set_kmsg_bytes(unsigned int bytes)
{
kmsg_bytes = bytes;
WRITE_ONCE(kmsg_bytes, bytes);
}
/* Tag each group of saved records with a sequence number */
@ -278,6 +278,7 @@ static void pstore_dump(struct kmsg_dumper *dumper,
struct kmsg_dump_detail *detail)
{
struct kmsg_dump_iter iter;
unsigned int remaining = READ_ONCE(kmsg_bytes);
unsigned long total = 0;
const char *why;
unsigned int part = 1;
@ -300,7 +301,7 @@ static void pstore_dump(struct kmsg_dumper *dumper,
kmsg_dump_rewind(&iter);
oopscount++;
while (total < kmsg_bytes) {
while (total < remaining) {
char *dst;
size_t dst_size;
int header_size;