From 7a4de924f90e4f04eb55c48a9197241daece0d95 Mon Sep 17 00:00:00 2001 From: Xiaomeng Tong Date: Fri, 8 Apr 2022 16:37:28 +0800 Subject: [PATCH] md: fix an incorrect NULL check in does_sb_need_changing commit fc8738343eefc4ea8afb6122826dea48eacde514 upstream. The bug is here: if (!rdev) The list iterator value 'rdev' will *always* be set and non-NULL by rdev_for_each(), so it is incorrect to assume that the iterator value will be NULL if the list is empty or no element found. Otherwise it will bypass the NULL check and lead to invalid memory access passing the check. To fix the bug, use a new variable 'iter' as the list iterator, while using the original variable 'rdev' as a dedicated pointer to point to the found element. Cc: stable@vger.kernel.org Fixes: 2aa82191ac36 ("md-cluster: Perform a lazy update") Acked-by: Guoqing Jiang Signed-off-by: Xiaomeng Tong Acked-by: Goldwyn Rodrigues Signed-off-by: Song Liu Signed-off-by: Greg Kroah-Hartman --- drivers/md/md.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 5e8706a66c318..d15edc3f6df4c 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -2427,14 +2427,16 @@ static void sync_sbs(struct mddev *mddev, int nospares) static bool does_sb_need_changing(struct mddev *mddev) { - struct md_rdev *rdev; + struct md_rdev *rdev = NULL, *iter; struct mdp_superblock_1 *sb; int role; /* Find a good rdev */ - rdev_for_each(rdev, mddev) - if ((rdev->raid_disk >= 0) && !test_bit(Faulty, &rdev->flags)) + rdev_for_each(iter, mddev) + if ((iter->raid_disk >= 0) && !test_bit(Faulty, &iter->flags)) { + rdev = iter; break; + } /* No good device found. */ if (!rdev) -- 2.47.3