From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Mahoney Subject: [PATCH] btrfsprogs: Fix use after free in close_ctree Date: Wed, 26 May 2010 11:40:02 -0400 Message-ID: <4BFD40D2.9090800@suse.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 To: linux-btrfs@vger.kernel.org Return-path: List-ID: After the roots are closed, root is freed. Yet close_ctree continues to use it. It works generally because no new memory is allocated in the interim, but with glibc malloc perturbing enabled, it crashes every time. This is because root->fs_info points to garbage. This patch uses the already-cached fs_info variable for the rest of the accesses and fixes the crash. This issue was reported at: https://bugzilla.novell.com/show_bug.cgi?id=603620 Signed-off-by: Jeff Mahoney --- disk-io.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) --- a/disk-io.c +++ b/disk-io.c @@ -971,13 +971,13 @@ int close_ctree(struct btrfs_root *root) if (fs_info->csum_root->node) free_extent_buffer(fs_info->csum_root->node); - if (root->fs_info->log_root_tree) { - if (root->fs_info->log_root_tree->node) - free_extent_buffer(root->fs_info->log_root_tree->node); - free(root->fs_info->log_root_tree); + if (fs_info->log_root_tree) { + if (fs_info->log_root_tree->node) + free_extent_buffer(fs_info->log_root_tree->node); + free(fs_info->log_root_tree); } - close_all_devices(root->fs_info); + close_all_devices(fs_info); extent_io_tree_cleanup(&fs_info->extent_cache); extent_io_tree_cleanup(&fs_info->free_space_cache); extent_io_tree_cleanup(&fs_info->block_group_cache); -- Jeff Mahoney SUSE Labs