From: Baokun Li libaokun1@huawei.com
mainline inclusion from mainline-v6.12-rc1 commit 5c0f4cc84d3a601c99bc5e6e6eb1cbda542cce95 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAYR8P CVE: CVE-2024-49983
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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When calling ext4_force_split_extent_at() in ext4_ext_replay_update_ex(), the 'ppath' is updated but it is the 'path' that is freed, thus potentially triggering a double-free in the following process:
ext4_ext_replay_update_ex ppath = path ext4_force_split_extent_at(&ppath) ext4_split_extent_at ext4_ext_insert_extent ext4_ext_create_new_leaf ext4_ext_grow_indepth ext4_find_extent if (depth > path[0].p_maxdepth) kfree(path) ---> path First freed *orig_path = path = NULL ---> null ppath kfree(path) ---> path double-free !!!
So drop the unnecessary ppath and use path directly to avoid this problem. And use ext4_find_extent() directly to update path, avoiding unnecessary memory allocation and freeing. Also, propagate the error returned by ext4_find_extent() instead of using strange error codes.
Fixes: 8016e29f4362 ("ext4: fast commit recovery path") Cc: stable@kernel.org Signed-off-by: Baokun Li libaokun1@huawei.com Reviewed-by: Jan Kara jack@suse.cz Reviewed-by: Ojaswin Mujoo ojaswin@linux.ibm.com Tested-by: Ojaswin Mujoo ojaswin@linux.ibm.com Link: https://patch.msgid.link/20240822023545.1994557-8-libaokun@huaweicloud.com Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Yongjian Sun sunyongjian1@huawei.com --- fs/ext4/extents.c | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-)
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index d618ff9b6b94..28d3175a063a 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -5905,7 +5905,7 @@ int ext4_clu_mapped(struct inode *inode, ext4_lblk_t lclu) int ext4_ext_replay_update_ex(struct inode *inode, ext4_lblk_t start, int len, int unwritten, ext4_fsblk_t pblk) { - struct ext4_ext_path *path = NULL, *ppath; + struct ext4_ext_path *path; struct ext4_extent *ex; int ret;
@@ -5921,30 +5921,29 @@ int ext4_ext_replay_update_ex(struct inode *inode, ext4_lblk_t start, if (le32_to_cpu(ex->ee_block) != start || ext4_ext_get_actual_len(ex) != len) { /* We need to split this extent to match our extent first */ - ppath = path; down_write(&EXT4_I(inode)->i_data_sem); - ret = ext4_force_split_extent_at(NULL, inode, &ppath, start, 1); + ret = ext4_force_split_extent_at(NULL, inode, &path, start, 1); up_write(&EXT4_I(inode)->i_data_sem); if (ret) goto out; - kfree(path); - path = ext4_find_extent(inode, start, NULL, 0); + + path = ext4_find_extent(inode, start, &path, 0); if (IS_ERR(path)) - return -1; - ppath = path; + return PTR_ERR(path); ex = path[path->p_depth].p_ext; WARN_ON(le32_to_cpu(ex->ee_block) != start); + if (ext4_ext_get_actual_len(ex) != len) { down_write(&EXT4_I(inode)->i_data_sem); - ret = ext4_force_split_extent_at(NULL, inode, &ppath, + ret = ext4_force_split_extent_at(NULL, inode, &path, start + len, 1); up_write(&EXT4_I(inode)->i_data_sem); if (ret) goto out; - kfree(path); - path = ext4_find_extent(inode, start, NULL, 0); + + path = ext4_find_extent(inode, start, &path, 0); if (IS_ERR(path)) - return -EINVAL; + return PTR_ERR(path); ex = path[path->p_depth].p_ext; } }