From: Xiaomeng Tong xiam0nd.tong@gmail.com
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 guoqing.jiang@linux.dev Signed-off-by: Xiaomeng Tong xiam0nd.tong@gmail.com Acked-by: Goldwyn Rodrigues rgoldwyn@suse.com Signed-off-by: Song Liu song@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/md/md.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
--- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -2427,14 +2427,16 @@ static void sync_sbs(struct mddev *mddev
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)