Prevent NULL pointer dereference in blkg_tryget() on EL8 kernels

blkg_tryget() as shipped in EL8 kernels does not seem to handle NULL @blkg as input; this is different from its mainline counterpart where NULL is accepted. To prevent dereferencing a NULL pointer when dealing with block devices which do not set a root_blkg on the request queue perform the NULL check in vdev_bio_associate_blkg(). Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Kjeld Schouten <[email protected]> Reviewed-by: Tony Hutter <[email protected]> Signed-off-by: loli10K <[email protected]> Closes #9546 Closes #9577
openzfs · Nov 13, 2019 · 7ba964c · 7ba964c
1 parent 8aaa10a
commit 7ba964c
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/module/os/linux/zfs/vdev_disk.c b/module/os/linux/zfs/vdev_disk.c
@@ -530,7 +530,7 @@ vdev_bio_associate_blkg(struct bio *bio)
 	ASSERT3P(q, !=, NULL);
 	ASSERT3P(bio->bi_blkg, ==, NULL);
 
-	if (blkg_tryget(q->root_blkg))
+	if (q->root_blkg && blkg_tryget(q->root_blkg))
 		bio->bi_blkg = q->root_blkg;
 }
 #define	bio_associate_blkg vdev_bio_associate_blkg