From: Xiaomeng Tong Date: Fri, 8 Apr 2022 08:37:28 +0000 (+0800) Subject: md: fix an incorrect NULL check in does_sb_need_changing X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=7907930218a6ef6b0f1eacce9dbe7b425c492117;p=linux.git 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 --- diff --git a/drivers/md/md.c b/drivers/md/md.c index 5ce2648cbe5b5..bbbc21c689f98 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -2628,14 +2628,16 @@ 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)