From: Daniel J Blueman <daniel.blueman@gmail.com>
Date: Thu, 23 Jun 2011 15:01:01 +0000 (+0800)
Subject: btrfs: fix oops on failure path
X-Git-Tag: Ubuntu-5.10.0-12.13~22794^2~23^2~3
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=068132bad1de70f85f5f6d12c36d64f8f7848d92;p=mirror_ubuntu-hirsute-kernel.git

btrfs: fix oops on failure path

If lookup_extent_backref fails, path->nodes[0] reasonably could be
null along with other callers of btrfs_print_leaf, so ensure we have a
valid extent buffer before dereferencing.

Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
---

diff --git a/fs/btrfs/print-tree.c b/fs/btrfs/print-tree.c
index fb2605d998e9..f38e452486b8 100644
--- a/fs/btrfs/print-tree.c
+++ b/fs/btrfs/print-tree.c
@@ -158,8 +158,7 @@ static void print_extent_ref_v0(struct extent_buffer *eb, int slot)
 void btrfs_print_leaf(struct btrfs_root *root, struct extent_buffer *l)
 {
 	int i;
-	u32 type;
-	u32 nr = btrfs_header_nritems(l);
+	u32 type, nr;
 	struct btrfs_item *item;
 	struct btrfs_root_item *ri;
 	struct btrfs_dir_item *di;
@@ -172,6 +171,11 @@ void btrfs_print_leaf(struct btrfs_root *root, struct extent_buffer *l)
 	struct btrfs_key key;
 	struct btrfs_key found_key;
 
+	if (!l)
+		return;
+
+	nr = btrfs_header_nritems(l);
+
 	printk(KERN_INFO "leaf %llu total ptrs %d free space %d\n",
 		(unsigned long long)btrfs_header_bytenr(l), nr,
 		btrfs_leaf_free_space(root, l));