From: Edward Adam Davis <eadavis@qq.com> stable inclusion from stable-v6.6.131 commit ecc50bfca9b5c2ee6aeef998181689b80477367b category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/14191 CVE: CVE-2026-31448 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 5422fe71d26d42af6c454ca9527faaad4e677d6c upstream. On the mkdir/mknod path, when mapping logical blocks to physical blocks, if inserting a new extent into the extent tree fails (in this example, because the file system disabled the huge file feature when marking the inode as dirty), ext4_ext_map_blocks() only calls ext4_free_blocks() to reclaim the physical block without deleting the corresponding data in the extent tree. This causes subsequent mkdir operations to reference the previously reclaimed physical block number again, even though this physical block is already being used by the xattr block. Therefore, a situation arises where both the directory and xattr are using the same buffer head block in memory simultaneously. The above causes ext4_xattr_block_set() to enter an infinite loop about "inserted" and cannot release the inode lock, ultimately leading to the 143s blocking problem mentioned in [1]. If the metadata is corrupted, then trying to remove some extent space can do even more harm. Also in case EXT4_GET_BLOCKS_DELALLOC_RESERVE was passed, remove space wrongly update quota information. Jan Kara suggests distinguishing between two cases: 1) The error is ENOSPC or EDQUOT - in this case the filesystem is fully consistent and we must maintain its consistency including all the accounting. However these errors can happen only early before we've inserted the extent into the extent tree. So current code works correctly for this case. 2) Some other error - this means metadata is corrupted. We should strive to do as few modifications as possible to limit damage. So I'd just skip freeing of allocated blocks. [1] INFO: task syz.0.17:5995 blocked for more than 143 seconds. Call Trace: inode_lock_nested include/linux/fs.h:1073 [inline] __start_dirop fs/namei.c:2923 [inline] start_dirop fs/namei.c:2934 [inline] Reported-by: syzbot+512459401510e2a9a39f@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=1659aaaaa8d9d11265d7 Tested-by: syzbot+1659aaaaa8d9d11265d7@syzkaller.appspotmail.com Reported-by: syzbot+1659aaaaa8d9d11265d7@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=512459401510e2a9a39f Tested-by: syzbot+1659aaaaa8d9d11265d7@syzkaller.appspotmail.com Signed-off-by: Edward Adam Davis <eadavis@qq.com> Reviewed-by: Jan Kara <jack@suse.cz> Tested-by: syzbot+512459401510e2a9a39f@syzkaller.appspotmail.com Link: https://patch.msgid.link/tencent_43696283A68450B761D76866C6F360E36705@qq.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Conflicts: fs/ext4/extents.c [Commit fb138df7d886 ("ext4: get rid of ppath in ext4_ext_insert_extent()") change the way to judge the result of ext4_ext_insert_extent() in ext4_ext_map_blocks().] Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com> --- fs/ext4/extents.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index dbc2154f7d4e..997c437685a0 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -4381,9 +4381,13 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, err = ext4_ext_insert_extent(handle, inode, &path, &newex, flags); if (err) { - if (allocated_clusters) { + /* + * Gracefully handle out of space conditions. If the filesystem + * is inconsistent, we'll just leak allocated blocks to avoid + * causing even more damage. + */ + if (allocated_clusters && (err == -EDQUOT || err == -ENOSPC)) { int fb_flags = 0; - /* * free data blocks we just allocated. * not a good idea to call discard here directly, -- 2.52.0