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Commit a967efb3 authored by Liu Bo's avatar Liu Bo Committed by David Sterba
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Btrfs: fix potential use-after-free for cloned bio 



KASAN reports that there is a use-after-free case of bio in btrfs_map_bio.

If we need to submit IOs to several disks at a time, the original bio
would get cloned and mapped to the destination disk, but we really should
use the original bio instead of a cloned bio to do the sanity check
because cloned bios are likely to be freed by its endio.

Reported-by: default avatarDiego <diegocg@gmail.com>
Signed-off-by: default avatarLiu Bo <bo.li.liu@oracle.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 97bf5a55

fs/btrfs/volumes.c

+1 −1
Original line number Diff line number Diff line
@@ -6213,7 +6213,7 @@ int btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio, 
	for (dev_nr = 0; dev_nr < total_devs; dev_nr++) {

		dev = bbio->stripes[dev_nr].dev;

		if (!dev || !dev->bdev ||

		    (bio_op(bio) == REQ_OP_WRITE && !dev->writeable)) {

		    (bio_op(first_bio) == REQ_OP_WRITE && !dev->writeable)) {

			bbio_error(bbio, first_bio, logical);

			continue;

		}