md: raid0/linear: fix dereference before null check on pointer mddev

Pointer mddev is being dereferenced with a test_bit call before mddev
is being null checked, this may cause a null pointer dereference. Fix
this by moving the null pointer checks to sanity check mddev before
it is dereferenced.

Addresses-Coverity: ("Dereference before null check")
Fixes: 62f7b1989c02 ("md raid0/linear: Mark array as 'broken' and fail BIOs if a member is gone")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Guilherme G. Piccoli <gpiccoli@canonical.com>
Signed-off-by: Song Liu <songliubraving@fb.com>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 8bb69c61afe0862be61b3972f5f5bc7ed0432293..49452149ac7234ace59b2637ed4a874228477f06 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -470,17 +470,18 @@ static blk_qc_t md_submit_bio(struct bio *bio)
        struct mddev *mddev = bio->bi_disk->private_data;
        unsigned int sectors;
 
-       if (unlikely(test_bit(MD_BROKEN, &mddev->flags)) && (rw == WRITE)) {
+       if (mddev == NULL || mddev->pers == NULL) {
                bio_io_error(bio);
                return BLK_QC_T_NONE;
        }
 
-       blk_queue_split(&bio);
-
-       if (mddev == NULL || mddev->pers == NULL) {
+       if (unlikely(test_bit(MD_BROKEN, &mddev->flags)) && (rw == WRITE)) {
                bio_io_error(bio);
                return BLK_QC_T_NONE;
        }
+
+       blk_queue_split(&bio);
+
        if (mddev->ro == 1 && unlikely(rw == WRITE)) {
                if (bio_sectors(bio) != 0)
                        bio->bi_status = BLK_STS_IOERR;