releases/6.8.6/block-prevent-division-by-zero-in-blk_rq_stat_sum.patch

   1 From 06c0345a5dbdc0181c0c00c008c983f4d3173be4 Mon Sep 17 00:00:00 2001
   2 From: Sasha Levin <sashal@kernel.org>
   3 Date: Tue, 5 Mar 2024 16:45:09 +0300
   4 Subject: block: prevent division by zero in blk_rq_stat_sum()
   5
   6 From: Roman Smirnov <r.smirnov@omp.ru>
   7
   8 [ Upstream commit 93f52fbeaf4b676b21acfe42a5152620e6770d02 ]
   9
  10 The expression dst->nr_samples + src->nr_samples may
  11 have zero value on overflow. It is necessary to add
  12 a check to avoid division by zero.
  13
  14 Found by Linux Verification Center (linuxtesting.org) with Svace.
  15
  16 Signed-off-by: Roman Smirnov <r.smirnov@omp.ru>
  17 Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
  18 Link: https://lore.kernel.org/r/20240305134509.23108-1-r.smirnov@omp.ru
  19 Signed-off-by: Jens Axboe <axboe@kernel.dk>
  20 Signed-off-by: Sasha Levin <sashal@kernel.org>
  21 ---
  22  block/blk-stat.c | 2 +-
  23  1 file changed, 1 insertion(+), 1 deletion(-)
  24
  25 diff --git a/block/blk-stat.c b/block/blk-stat.c
  26 index 7ff76ae6c76a9..e42c263e53fb9 100644
  27 --- a/block/blk-stat.c
  28 +++ b/block/blk-stat.c
  29 @@ -27,7 +27,7 @@ void blk_rq_stat_init(struct blk_rq_stat *stat)
  30  /* src is a per-cpu stat, mean isn't initialized */
  31  void blk_rq_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src)
  32  {
  33 -       if (!src->nr_samples)
  34 +       if (dst->nr_samples + src->nr_samples <= dst->nr_samples)
  35                 return;
  36
  37         dst->min = min(dst->min, src->min);
  38 --
  39 2.43.0
  40