Patch "Btrfs: fix potential use-after-free for cloned bio" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    Btrfs: fix potential use-after-free for cloned bio

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     btrfs-fix-potential-use-after-free-for-cloned-bio.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Thu Oct  5 10:28:31 CEST 2017
From: Liu Bo <bo.li.liu@oracle.com>
Date: Mon, 10 Apr 2017 12:36:26 -0700
Subject: Btrfs: fix potential use-after-free for cloned bio

From: Liu Bo <bo.li.liu@oracle.com>


[ Upstream commit a967efb30b3afa3d858edd6a17f544f9e9e46eea ]

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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/btrfs/volumes.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6226,7 +6226,7 @@ int btrfs_map_bio(struct btrfs_root *roo
 	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;
 		}


Patches currently in stable-queue which might be from bo.li.liu@oracle.com are

queue-4.9/btrfs-fix-potential-use-after-free-for-cloned-bio.patch
queue-4.9/btrfs-fix-segmentation-fault-when-doing-dio-read.patch