| From 0be698ecbe4471fcad80e81ec6a05001421041b3 Mon Sep 17 00:00:00 2001 |
| From: Ye Bin <yebin10@huawei.com> |
| Date: Thu, 14 Apr 2022 10:52:23 +0800 |
| Subject: ext4: fix use-after-free in ext4_rename_dir_prepare |
| |
| From: Ye Bin <yebin10@huawei.com> |
| |
| commit 0be698ecbe4471fcad80e81ec6a05001421041b3 upstream. |
| |
| We got issue as follows: |
| EXT4-fs (loop0): mounted filesystem without journal. Opts: ,errors=continue |
| ext4_get_first_dir_block: bh->b_data=0xffff88810bee6000 len=34478 |
| ext4_get_first_dir_block: *parent_de=0xffff88810beee6ae bh->b_data=0xffff88810bee6000 |
| ext4_rename_dir_prepare: [1] parent_de=0xffff88810beee6ae |
| ================================================================== |
| BUG: KASAN: use-after-free in ext4_rename_dir_prepare+0x152/0x220 |
| Read of size 4 at addr ffff88810beee6ae by task rep/1895 |
| |
| CPU: 13 PID: 1895 Comm: rep Not tainted 5.10.0+ #241 |
| Call Trace: |
| dump_stack+0xbe/0xf9 |
| print_address_description.constprop.0+0x1e/0x220 |
| kasan_report.cold+0x37/0x7f |
| ext4_rename_dir_prepare+0x152/0x220 |
| ext4_rename+0xf44/0x1ad0 |
| ext4_rename2+0x11c/0x170 |
| vfs_rename+0xa84/0x1440 |
| do_renameat2+0x683/0x8f0 |
| __x64_sys_renameat+0x53/0x60 |
| do_syscall_64+0x33/0x40 |
| entry_SYSCALL_64_after_hwframe+0x44/0xa9 |
| RIP: 0033:0x7f45a6fc41c9 |
| RSP: 002b:00007ffc5a470218 EFLAGS: 00000246 ORIG_RAX: 0000000000000108 |
| RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f45a6fc41c9 |
| RDX: 0000000000000005 RSI: 0000000020000180 RDI: 0000000000000005 |
| RBP: 00007ffc5a470240 R08: 00007ffc5a470160 R09: 0000000020000080 |
| R10: 00000000200001c0 R11: 0000000000000246 R12: 0000000000400bb0 |
| R13: 00007ffc5a470320 R14: 0000000000000000 R15: 0000000000000000 |
| |
| The buggy address belongs to the page: |
| page:00000000440015ce refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x10beee |
| flags: 0x200000000000000() |
| raw: 0200000000000000 ffffea00043ff4c8 ffffea0004325608 0000000000000000 |
| raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000 |
| page dumped because: kasan: bad access detected |
| |
| Memory state around the buggy address: |
| ffff88810beee580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |
| ffff88810beee600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |
| >ffff88810beee680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |
| ^ |
| ffff88810beee700: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |
| ffff88810beee780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |
| ================================================================== |
| Disabling lock debugging due to kernel taint |
| ext4_rename_dir_prepare: [2] parent_de->inode=3537895424 |
| ext4_rename_dir_prepare: [3] dir=0xffff888124170140 |
| ext4_rename_dir_prepare: [4] ino=2 |
| ext4_rename_dir_prepare: ent->dir->i_ino=2 parent=-757071872 |
| |
| Reason is first directory entry which 'rec_len' is 34478, then will get illegal |
| parent entry. Now, we do not check directory entry after read directory block |
| in 'ext4_get_first_dir_block'. |
| To solve this issue, check directory entry in 'ext4_get_first_dir_block'. |
| |
| [ Trigger an ext4_error() instead of just warning if the directory is |
| missing a '.' or '..' entry. Also make sure we return an error code |
| if the file system is corrupted. -TYT ] |
| |
| Signed-off-by: Ye Bin <yebin10@huawei.com> |
| Reviewed-by: Jan Kara <jack@suse.cz> |
| Link: https://lore.kernel.org/r/20220414025223.4113128-1-yebin10@huawei.com |
| Signed-off-by: Theodore Ts'o <tytso@mit.edu> |
| Cc: stable@kernel.org |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| fs/ext4/namei.c | 30 +++++++++++++++++++++++++++--- |
| 1 file changed, 27 insertions(+), 3 deletions(-) |
| |
| --- a/fs/ext4/namei.c |
| +++ b/fs/ext4/namei.c |
| @@ -3318,6 +3318,9 @@ static struct buffer_head *ext4_get_firs |
| struct buffer_head *bh; |
| |
| if (!ext4_has_inline_data(inode)) { |
| + struct ext4_dir_entry_2 *de; |
| + unsigned int offset; |
| + |
| /* The first directory block must not be a hole, so |
| * treat it as DIRENT_HTREE |
| */ |
| @@ -3326,9 +3329,30 @@ static struct buffer_head *ext4_get_firs |
| *retval = PTR_ERR(bh); |
| return NULL; |
| } |
| - *parent_de = ext4_next_entry( |
| - (struct ext4_dir_entry_2 *)bh->b_data, |
| - inode->i_sb->s_blocksize); |
| + |
| + de = (struct ext4_dir_entry_2 *) bh->b_data; |
| + if (ext4_check_dir_entry(inode, NULL, de, bh, bh->b_data, |
| + bh->b_size, 0) || |
| + le32_to_cpu(de->inode) != inode->i_ino || |
| + strcmp(".", de->name)) { |
| + EXT4_ERROR_INODE(inode, "directory missing '.'"); |
| + brelse(bh); |
| + *retval = -EFSCORRUPTED; |
| + return NULL; |
| + } |
| + offset = ext4_rec_len_from_disk(de->rec_len, |
| + inode->i_sb->s_blocksize); |
| + de = ext4_next_entry(de, inode->i_sb->s_blocksize); |
| + if (ext4_check_dir_entry(inode, NULL, de, bh, bh->b_data, |
| + bh->b_size, offset) || |
| + le32_to_cpu(de->inode) == 0 || strcmp("..", de->name)) { |
| + EXT4_ERROR_INODE(inode, "directory missing '..'"); |
| + brelse(bh); |
| + *retval = -EFSCORRUPTED; |
| + return NULL; |
| + } |
| + *parent_de = de; |
| + |
| return bh; |
| } |
| |