From c7967fc1499beb9b70bb9d33525fb0b384af8883 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Tue, 15 Oct 2019 10:54:39 +0100 Subject: [PATCH] Btrfs: fix qgroup double free after failure to reserve metadata for delalloc If we fail to reserve metadata for delalloc operations we end up releasing the previously reserved qgroup amount twice, once explicitly under the 'out_qgroup' label by calling btrfs_qgroup_free_meta_prealloc() and once again, under label 'out_fail', by calling btrfs_inode_rsv_release() with a value of 'true' for its 'qgroup_free' argument, which results in btrfs_qgroup_free_meta_prealloc() being called again, so we end up having a double free. Also if we fail to reserve the necessary qgroup amount, we jump to the label 'out_fail', which calls btrfs_inode_rsv_release() and that in turns calls btrfs_qgroup_free_meta_prealloc(), even though we weren't able to reserve any qgroup amount. So we freed some amount we never reserved. So fix this by removing the call to btrfs_inode_rsv_release() in the failure path, since it's not necessary at all as we haven't changed the inode's block reserve in any way at this point. Fixes: c8eaeac7b73434 ("btrfs: reserve delalloc metadata differently") CC: stable@vger.kernel.org # 5.2+ Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/delalloc-space.c | 1 - 1 file changed, 1 deletion(-) diff --git a/fs/btrfs/delalloc-space.c b/fs/btrfs/delalloc-space.c index 571e7b31ea2f..db9f2c58eb4a 100644 --- a/fs/btrfs/delalloc-space.c +++ b/fs/btrfs/delalloc-space.c @@ -381,7 +381,6 @@ int btrfs_delalloc_reserve_metadata(struct btrfs_inode *inode, u64 num_bytes) out_qgroup: btrfs_qgroup_free_meta_prealloc(root, qgroup_reserve); out_fail: - btrfs_inode_rsv_release(inode, true); if (delalloc_lock) mutex_unlock(&inode->delalloc_mutex); return ret;