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Message-ID: <20240324170743.546858-2-sashal@kernel.org>
Date: Sun, 24 Mar 2024 13:07:41 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
stable@...r.kernel.org
Cc: Roman Smirnov <r.smirnov@....ru>,
Sergey Shtylyov <s.shtylyov@....ru>,
Jens Axboe <axboe@...nel.dk>,
Sasha Levin <sashal@...nel.org>,
linux-block@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 2/2] block: prevent division by zero in blk_rq_stat_sum()
From: Roman Smirnov <r.smirnov@....ru>
[ 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@....ru>
Reviewed-by: Sergey Shtylyov <s.shtylyov@....ru>
Link: https://lore.kernel.org/r/20240305134509.23108-1-r.smirnov@omp.ru
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
block/blk-stat.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/blk-stat.c b/block/blk-stat.c
index 7587b1c3caaf5..507ac714423bd 100644
--- a/block/blk-stat.c
+++ b/block/blk-stat.c
@@ -27,7 +27,7 @@ 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);
--
2.43.0
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