From 5889d3e4cf3ad851f0b1b1657d04e5f88b6142ac Mon Sep 17 00:00:00 2001 From: Xiaomeng Tong Date: Fri, 8 Jul 2022 17:45:48 +0800 Subject: [PATCH] md: fix an incorrect NULL check in does_sb_need_changing stable inclusion from stable-4.19.247 commit fcb51189503b2f5a254910b85ad1b03295e09aab category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5FNPY CVE: NA -------------------------------- 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 Signed-off-by: Yongqiang Liu Signed-off-by: Laibin Qiu --- 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 8a68ff71fbbf..1aa40509f90e 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -2483,14 +2483,16 @@ 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) -- GitLab