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Prevent NULL pointer dereference in blkg_tryget() on EL8 kernels
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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 openzfs#9546 
Closes openzfs#9577
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loli10K authored and behlendorf committed Nov 13, 2019
1 parent 8aaa10a commit 7ba964c
Showing 1 changed file with 1 addition and 1 deletion.
2 changes: 1 addition & 1 deletion module/os/linux/zfs/vdev_disk.c
Original file line number Diff line number Diff line change
Expand Up @@ -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
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