| From | Jiri Slaby <> | Subject | [PATCH 3.12 094/123] btrfs: fix use after free iterating extrefs | Date | Wed, 28 Oct 2015 14:53:25 +0100 |
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From: Chris Mason <clm@fb.com>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
commit dc6c5fb3b514221f2e9d21ee626a9d95d3418dff upstream.
The code for btrfs inode-resolve has never worked properly for files with enough hard links to trigger extrefs. It was trying to get the leaf out of a path after freeing the path:
btrfs_release_path(path); leaf = path->nodes[0]; item_size = btrfs_item_size_nr(leaf, slot);
The fix here is to use the extent buffer we cloned just a little higher up to avoid deadlocks caused by using the leaf in the path.
Signed-off-by: Chris Mason <clm@fb.com> cc: Mark Fasheh <mfasheh@suse.de> Reviewed-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: Mark Fasheh <mfasheh@suse.de> Signed-off-by: Jiri Slaby <jslaby@suse.cz> --- fs/btrfs/backref.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c index 53039de1495d..db6818878462 100644 --- a/fs/btrfs/backref.c +++ b/fs/btrfs/backref.c @@ -1668,7 +1668,6 @@ static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root, int found = 0; struct extent_buffer *eb; struct btrfs_inode_extref *extref; - struct extent_buffer *leaf; u32 item_size; u32 cur_offset; unsigned long ptr; @@ -1693,9 +1692,8 @@ static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root, btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK); btrfs_release_path(path); - leaf = path->nodes[0]; - item_size = btrfs_item_size_nr(leaf, path->slots[0]); - ptr = btrfs_item_ptr_offset(leaf, path->slots[0]); + item_size = btrfs_item_size_nr(eb, path->slots[0]); + ptr = btrfs_item_ptr_offset(eb, path->slots[0]); cur_offset = 0; while (cur_offset < item_size) { @@ -1709,7 +1707,7 @@ static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root, if (ret) break; - cur_offset += btrfs_inode_extref_name_len(leaf, extref); + cur_offset += btrfs_inode_extref_name_len(eb, extref); cur_offset += sizeof(*extref); } btrfs_tree_read_unlock_blocking(eb); -- 2.6.2
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