From: Xiaomeng Tong <xiam0nd.tong@gmail.com> stable inclusion from stable-v5.10.121 commit 2401f1cf3dee6974d799a4387f0c5d98cec29326 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5L6CQ Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- 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> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Acked-by: Xie XiuQi <xiexiuqi@huawei.com> --- 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 10d9a8bed604..556c136ce743 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -2637,14 +2637,16 @@ 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) -- 2.20.1