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FAILED: patch "[PATCH] btrfs: fix use after free iterating extrefs" failed to apply to 3.10-stable tree

PATCH [email protected] 1 participant 1 message Oct 23, 2015

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The patch below does not apply to the 3.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

Quoted 1 line

From dc6c5fb3b514221f2e9d21ee626a9d95d3418dff Mon Sep 17 00:00:00 2001

From: Chris Mason <[email protected]>
Date: Tue, 13 Oct 2015 14:06:48 -0400
Subject: [PATCH] btrfs: fix use after free iterating extrefs

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 <[email protected]>
cc [email protected] # v3.7+
cc Mark Fasheh <[email protected]>
Reviewed-by Filipe Manana <[email protected]>
Reviewed-by Mark Fasheh <[email protected]>
fs/btrfs/backref.c +3 -5
index ecbc63d3143e..9a2ec79e8cfb 100644
@@ -1828,7 +1828,6 @@ 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;

@@ -1856,9 +1855,8 @@ 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, slot);
-		ptr = btrfs_item_ptr_offset(leaf, slot);
+		item_size = btrfs_item_size_nr(eb, slot);
+		ptr = btrfs_item_ptr_offset(eb, slot);
 		cur_offset = 0;
 
 		while (cur_offset < item_size) {

@@ -1872,7 +1870,7 @@ 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);