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authorZhao Lei <zhaolei@cn.fujitsu.com>2015-07-15 21:02:09 +0800
committerChris Mason <clm@fb.com>2015-07-22 18:20:52 -0700
commit95ab1f64908795a2edd6b847eca94a0c63a44be4 (patch)
tree34b4e05f9ed2b15cc7488d9f7bd60cbcc9969da5 /fs
parentbtrfs: Fix lockdep warning of btrfs_run_delayed_iputs() (diff)
downloadlinux-dev-95ab1f64908795a2edd6b847eca94a0c63a44be4.tar.xz
linux-dev-95ab1f64908795a2edd6b847eca94a0c63a44be4.zip
btrfs: Avoid NULL pointer dereference of free_extent_buffer when read_tree_block() fail
When read_tree_block() failed, we can see following dmesg: [ 134.371389] BUG: unable to handle kernel NULL pointer dereference at 0000000000000063 [ 134.372236] IP: [<ffffffff813a4a51>] free_extent_buffer+0x21/0x90 [ 134.372236] PGD 0 [ 134.372236] Oops: 0000 [#1] SMP [ 134.372236] Modules linked in: [ 134.372236] CPU: 0 PID: 2289 Comm: mount Not tainted 4.2.0-rc1_HEAD_c65b99f046843d2455aa231747b5a07a999a9f3d_+ #115 [ 134.372236] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5.1-0-g8936dbb-20141113_115728-nilsson.home.kraxel.org 04/01/2014 [ 134.372236] task: ffff88003b6e1a00 ti: ffff880011e60000 task.ti: ffff880011e60000 [ 134.372236] RIP: 0010:[<ffffffff813a4a51>] [<ffffffff813a4a51>] free_extent_buffer+0x21/0x90 ... [ 134.372236] Call Trace: [ 134.372236] [<ffffffff81379aa1>] free_root_extent_buffers+0x91/0xb0 [ 134.372236] [<ffffffff81379c3d>] free_root_pointers+0x17d/0x190 [ 134.372236] [<ffffffff813801b0>] open_ctree+0x1ca0/0x25b0 [ 134.372236] [<ffffffff8144d017>] ? disk_name+0x97/0xb0 [ 134.372236] [<ffffffff813558aa>] btrfs_mount+0x8fa/0xab0 ... Reason: read_tree_block() changed to return error number on fail, and this value(not NULL) is set to tree_root->node, then subsequent code will run to: free_root_pointers() ->free_root_extent_buffers() ->free_extent_buffer() ->atomic_read((extent_buffer *)(-E_XXX)->refs); and trigger above error. Fix: Set tree_root->node to NULL on fail to make error_handle code happy. Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com> Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/disk-io.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index e5aad7f535aa..84cbbb2d562e 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2842,6 +2842,7 @@ int open_ctree(struct super_block *sb,
!extent_buffer_uptodate(chunk_root->node)) {
printk(KERN_ERR "BTRFS: failed to read chunk root on %s\n",
sb->s_id);
+ chunk_root->node = NULL;
goto fail_tree_roots;
}
btrfs_set_root_node(&chunk_root->root_item, chunk_root->node);
@@ -2879,7 +2880,7 @@ retry_root_backup:
!extent_buffer_uptodate(tree_root->node)) {
printk(KERN_WARNING "BTRFS: failed to read tree root on %s\n",
sb->s_id);
-
+ tree_root->node = NULL;
goto recovery_tree_root;
}