[PATCH 3.18 025/104] bcache: fix input overflow to cache set sysfs file io_error_halflife

Greg Kroah-Hartman
2019-04-24T17:11:51Z

[ Upstream commit a91fbda49f746119828f7e8ad0f0aa2ab0578f65 ]

Cache set sysfs entry io_error_halflife is used to set c->error_decay.
c->error_decay is in type unsigned int, and it is converted by
strtoul_or_return(), therefore overflow to c->error_decay is possible
for a large input value.

This patch fixes the overflow by using strtoul_safe_clamp() to convert
input string to an unsigned long value in range [0, UINT_MAX], then
divides by 88 and set it to c->error_decay.

Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/md/bcache/sysfs.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index 5a5c1f1bd8a5..87daccbbc61b 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -645,8 +645,17 @@ STORE(__bch_cache_set)
c->error_limit = strtoul_or_return(buf) << IO_ERROR_SHIFT;

/* See count_io_errors() for why 88 */
- if (attr == &sysfs_io_error_halflife)
- c->error_decay = strtoul_or_return(buf) / 88;
+ if (attr == &sysfs_io_error_halflife) {
+ unsigned long v = 0;
+ ssize_t ret;
+
+ ret = strtoul_safe_clamp(buf, v, 0, UINT_MAX);
+ if (!ret) {
+ c->error_decay = v / 88;
+ return size;
+ }
+ return ret;
+ }

sysfs_strtoul(journal_delay_ms, c->journal_delay_ms);
sysfs_strtoul(verify, c->verify);
--
2.19.1