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authorNikolay Borisov <nborisov@suse.com>2018-01-30 16:07:37 +0200
committerDavid Sterba <dsterba@suse.com>2018-02-05 17:15:14 +0100
commitfd649f10c3d21ee9d7542c609f29978bdf73ab94 (patch)
treea79f74afd161f3b51f6016ad806a60c89e9c2e20
parent627e08738e4315458c5df06358ce7a65cfdd635d (diff)
btrfs: Fix use-after-free when cleaning up fs_devs with a single stale device
Commit 4fde46f0cc71 ("Btrfs: free the stale device") introduced btrfs_free_stale_device which iterates the device lists for all registered btrfs filesystems and deletes those devices which aren't mounted. In a btrfs_devices structure has only 1 device attached to it and it is unused then btrfs_free_stale_devices will proceed to also free the btrfs_fs_devices struct itself. Currently this leads to a use after free since list_for_each_entry will try to perform a check on the already freed memory to see if it has to terminate the loop. The fix is to use 'break' when we know we are freeing the current fs_devs. Fixes: 4fde46f0cc71 ("Btrfs: free the stale device") Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
-rw-r--r--fs/btrfs/volumes.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b5036bd69e6a..2ceb924ca0d6 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -645,6 +645,7 @@ static void btrfs_free_stale_devices(const char *path,
btrfs_sysfs_remove_fsid(fs_devs);
list_del(&fs_devs->list);
free_fs_devices(fs_devs);
+ break;
} else {
fs_devs->num_devices--;
list_del(&dev->dev_list);