Commit fc873834 authored by Xiaomeng Tong's avatar Xiaomeng Tong Committed by Song Liu
Browse files

md: fix an incorrect NULL check in does_sb_need_changing 



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: 2aa82191 ("md-cluster: Perform a lazy update")
Acked-by: default avatarGuoqing Jiang <guoqing.jiang@linux.dev>
Signed-off-by: default avatarXiaomeng Tong <xiam0nd.tong@gmail.com>
Acked-by: default avatarGoldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: default avatarSong Liu <song@kernel.org>
parent 57668f0a

drivers/md/md.c

+5 −3
Original line number Diff line number Diff line
@@ -2627,14 +2627,16 @@ 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)