Commit a967efb3 authored Apr 10, 2017 by Liu Bo Committed by David Sterba Apr 11, 2017

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: Diego <diegocg@gmail.com>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David 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;
		}

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