If the string opt_string is small, the function memcmp can access bytes
that are beyond the terminating nul character. In theory, it could cause
segfault, if opt_string were located just below some unmapped memory.
This patch changes memcmp to strncmp, so that we don't read bytes beyond
the end of the string.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v4.12+
---
drivers/md/dm-integrity.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
Index: linux-2.6/drivers/md/dm-integrity.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-integrity.c 2019-03-12 15:33:17.000000000 +0100
+++ linux-2.6/drivers/md/dm-integrity.c 2019-03-12 15:34:49.000000000 +0100
@@ -3185,7 +3185,7 @@ static int dm_integrity_ctr(struct dm_ta
journal_watermark = val;
else if (sscanf(opt_string, "commit_time:%u%c", &val, &dummy) == 1)
sync_msec = val;
- else if (!memcmp(opt_string, "meta_device:", strlen("meta_device:"))) {
+ else if (!strncmp(opt_string, "meta_device:", strlen("meta_device:"))) {
if (ic->meta_dev) {
dm_put_device(ti, ic->meta_dev);
ic->meta_dev = NULL;
@@ -3204,17 +3204,17 @@ static int dm_integrity_ctr(struct dm_ta
goto bad;
}
ic->sectors_per_block = val >> SECTOR_SHIFT;
- } else if (!memcmp(opt_string, "internal_hash:", strlen("internal_hash:"))) {
+ } else if (!strncmp(opt_string, "internal_hash:", strlen("internal_hash:"))) {
r = get_alg_and_key(opt_string, &ic->internal_hash_alg, &ti->error,
"Invalid internal_hash argument");
if (r)
goto bad;
- } else if (!memcmp(opt_string, "journal_crypt:", strlen("journal_crypt:"))) {
+ } else if (!strncmp(opt_string, "journal_crypt:", strlen("journal_crypt:"))) {
r = get_alg_and_key(opt_string, &ic->journal_crypt_alg, &ti->error,
"Invalid journal_crypt argument");
if (r)
goto bad;
- } else if (!memcmp(opt_string, "journal_mac:", strlen("journal_mac:"))) {
+ } else if (!strncmp(opt_string, "journal_mac:", strlen("journal_mac:"))) {
r = get_alg_and_key(opt_string, &ic->journal_mac_alg, &ti->error,
"Invalid journal_mac argument");
if (r)
--
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