This is a note to let you know that I've just added the patch titled
block: prevent division by zero in blk_rq_stat_sum()
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
block-prevent-division-by-zero-in-blk_rq_stat_sum.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit d5a2ba7f3c05dba0dacb7bfc62bbfbcc74f608d2
Author: Roman Smirnov <r.smirnov@xxxxxx>
Date: Tue Mar 5 16:45:09 2024 +0300
block: prevent division by zero in blk_rq_stat_sum()
[ Upstream commit 93f52fbeaf4b676b21acfe42a5152620e6770d02 ]
The expression dst->nr_samples + src->nr_samples may
have zero value on overflow. It is necessary to add
a check to avoid division by zero.
Found by Linux Verification Center (linuxtesting.org) with Svace.
Signed-off-by: Roman Smirnov <r.smirnov@xxxxxx>
Reviewed-by: Sergey Shtylyov <s.shtylyov@xxxxxx>
Link: https://lore.kernel.org/r/20240305134509.23108-1-r.smirnov@xxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/block/blk-stat.c b/block/blk-stat.c
index 940f15d600f8a..af482d8f9f7a4 100644
--- a/block/blk-stat.c
+++ b/block/blk-stat.c
@@ -28,7 +28,7 @@ void blk_rq_stat_init(struct blk_rq_stat *stat)
/* src is a per-cpu stat, mean isn't initialized */
void blk_rq_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src)
{
- if (!src->nr_samples)
+ if (dst->nr_samples + src->nr_samples <= dst->nr_samples)
return;
dst->min = min(dst->min, src->min);
