Re: [RESEND PATCH] btrfs: Fix UAF when cleaning up fs_devs with a single stale device
On Tue, Jan 30, 2018 at 04:07:37PM +0200, Nikolay Borisov wrote: > 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 UAF > since list_for_each_entry will try to perform a check on the already- > freed memory to see if it has to terminated 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 Added to next, thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[RESEND PATCH] btrfs: Fix UAF 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 UAF since list_for_each_entry will try to perform a check on the already- freed memory to see if it has to terminated 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 --- Changed the subject to make it more descriptive fs/btrfs/volumes.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index f7147740b68e..c3ab55336ee0 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); -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html