From 4549e55f71cfae143472a35e8e31e206ffbabe58 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Tue, 23 Mar 2021 12:01:03 +0000 Subject: [PATCH] btrfs: avoid double put of block group when emptying cluster MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit stable inclusion from stable-5.10.22 commit a01415e5e862a60a52b10081532e09f9b3503592 bugzilla: 50796 -------------------------------- commit 95c85fba1f64c3249c67f0078a29f8a125078189 upstream. It's wrong calling btrfs_put_block_group in __btrfs_return_cluster_to_free_space if the block group passed is different than the block group the cluster represents. As this means the cluster doesn't have a reference to the passed block group. This results in double put and a use-after-free bug. Fix this by simply bailing if the block group we passed in does not match the block group on the cluster. Fixes: fa9c0d795f7b ("Btrfs: rework allocation clustering") CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Josef Bacik Reviewed-by: David Sterba [ update changelog ] Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman Signed-off-by: Chen Jun Acked-by:  Weilong Chen Signed-off-by: Zheng Zengkai --- fs/btrfs/free-space-cache.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index ae4059ce2f84..9ebc8e2237e8 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -2714,8 +2714,10 @@ static void __btrfs_return_cluster_to_free_space( struct rb_node *node; spin_lock(&cluster->lock); - if (cluster->block_group != block_group) - goto out; + if (cluster->block_group != block_group) { + spin_unlock(&cluster->lock); + return; + } cluster->block_group = NULL; cluster->window_start = 0; @@ -2753,8 +2755,6 @@ static void __btrfs_return_cluster_to_free_space( entry->offset, &entry->offset_index, bitmap); } cluster->root = RB_ROOT; - -out: spin_unlock(&cluster->lock); btrfs_put_block_group(block_group); } -- GitLab