From: Xiaomeng Tong xiam0nd.tong@gmail.com
stable inclusion from stable-4.19.247 commit fcb51189503b2f5a254910b85ad1b03295e09aab category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5FNPY CVE: NA
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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: Yongqiang Liu liuyongqiang13@huawei.com Signed-off-by: Laibin Qiu qiulaibin@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 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)