2022-06-24 21:19 GMT+09:00, Anton Altaparmakov anton@tuxera.com:
Hi,
On 24 Jun 2022, at 03:33, Namjae Jeon <linkinjeon@kernel.orgmailto:linkinjeon@kernel.org> wrote:
2022-06-24 2:08 GMT+09:00, Eric Biggers <ebiggers@kernel.orgmailto:ebiggers@kernel.org>: On Thu, Jun 23, 2022 at 09:49:56AM +0000, cgel.zte@gmail.commailto:cgel.zte@gmail.com wrote: From: xu xin <xu.xin16@zte.com.cnmailto:xu.xin16@zte.com.cn>
As the bug description at https://lore.kernel.org/lkml/20220623033635.973929-1-xu.xin16@zte.com.cn/ attckers can use this bug to crash the system.
So to avoid panic, remove the BUG_ON, and use ntfs_warning to output a warning to the syslog and return instead until someone really solve the problem.
Cc: stable@vger.kernel.org Reported-by: Zeal Robot zealci@zte.com.cn Reported-by: syzbot+6a5a7672f663cce8b156@syzkaller.appspotmail.com Reviewed-by: Songyi Zhang zhang.songyi@zte.com.cn Reviewed-by: Yang Yang yang.yang29@zte.com.cn Reviewed-by: Jiang Xuexinjiang.xuexin@zte.com.cn Reviewed-by: Zhang wenyazhang.wenya1@zte.com.cn Signed-off-by: xu xin xu.xin16@zte.com.cn
Change for v2:
- Use ntfs_warning instead of WARN().
- Add the tag Cc: stable@vger.kernel.org.
fs/ntfs/aops.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c index 5f4fb6ca6f2e..84d68efb4ace 100644 --- a/fs/ntfs/aops.c +++ b/fs/ntfs/aops.c @@ -183,7 +183,12 @@ static int ntfs_read_block(struct page *page) vol = ni->vol;
/* $MFT/$DATA must have its complete runlist in memory at all times. */
- BUG_ON(!ni->runlist.rl && !ni->mft_no && !NInoAttr(ni));
- if (unlikely(!ni->runlist.rl && !ni->mft_no && !NInoAttr(ni))) {
- ntfs_warning(vi->i_sb, "Error because ni->runlist.rl, ni->mft_no, "
- "and NInoAttr(ni) is null.");
- unlock_page(page);
- return -EINVAL;
- }
A better warning message that doesn't rely on implementation details (struct field and macro names) would be "Runlist of $MFT/$DATA is not cached". Also, why does this situation happen in the first place? Is there a way to prevent this situation in the first place?
ntfs_mapping_pairs_decompress() should return error pointer instead of NULL.
Callers is checking error value using IS_ERR(). and the mapping pairs array of @MFT entry is empty, I think it's corrupted, it should cause mount failure.
NAK
Sorry but this patch is incorrect. It is perfectly valid to have an empty non-resident attribute. E.g. if you truncate a file to zero size this is exactly what you will get on-disk and when you then unmount and mount next time and try to access that file with your patch you will now get an -EIO error trying to access the file and you will not be able to write to the file nor truncate it as you will keep getting the i/o error.
Sorry, I can't reproduce the issue you described?
root@linkinjeon-Z10PA-D8-Series:/mnt/test# ls -al total 5928 drwx------ 1 root root 4096 6월 24 23:01 . drwxr-xr-x 7 root root 4096 5월 29 12:47 .. -rw------- 1 root root 6059409 9월 22 2020 foo drwx------ 1 root root 0 6월 24 22:30 'System Volume Information' root@linkinjeon-Z10PA-D8-Series:/mnt/test# truncate -s 0 foo root@linkinjeon-Z10PA-D8-Series:/mnt/test# ls -al total 8 drwx------ 1 root root 4096 6월 24 23:01 . drwxr-xr-x 7 root root 4096 5월 29 12:47 .. -rw------- 1 root root 0 6월 24 23:11 foo drwx------ 1 root root 0 6월 24 22:30 'System Volume Information' root@linkinjeon-Z10PA-D8-Series:/mnt/test# cd .. root@linkinjeon-Z10PA-D8-Series:/mnt# sudo umount /mnt/test root@linkinjeon-Z10PA-D8-Series:/mnt# sudo mount -t ntfs /dev/sde2 /mnt/test/ root@linkinjeon-Z10PA-D8-Series:/mnt# cd /mnt/test/ root@linkinjeon-Z10PA-D8-Series:/mnt/test# cat foo root@linkinjeon-Z10PA-D8-Series:/mnt/test# truncate -s 1048576 foo root@linkinjeon-Z10PA-D8-Series:/mnt/test# ls -al total 1032 drwx------ 1 root root 4096 6월 24 23:01 . drwxr-xr-x 7 root root 4096 5월 29 12:47 .. -rw------- 1 root root 1048576 6월 24 23:12 foo drwx------ 1 root root 0 6월 24 22:30 'System Volume Information' root@linkinjeon-Z10PA-D8-Series:/mnt/test# echo "hello world" > foo root@linkinjeon-Z10PA-D8-Series:/mnt/test# cat foo hello world
The correct solution is to use IS_ERR_OR_NULL() in places where an empty attribute is not acceptable. Such a case is for example when mounting the $MFT::$DATA::unnamed attribute cannot be empty which should then be addressed inside in fs/ntfs/inode.c::ntfs_read_inode_mount(). There may be more call sites to ntfs_mapping_pairs_decompress() which require similar treatment. Need to go through the code to see...
I think that it is needed everywhere that calls it. Am I missing something ?
I can not understand why the below code is needed in ntfs_mapping_pairs_decompress().
/* If the mapping pairs array is valid but empty, nothing to do. */ if (!vcn && !*buf) { return old_rl; }
There is no description in patch. and this code is not in ntfs_mapping_pairs_decompress() in ntfs-3g. Is there any case the caller get NULL runlist pointer from ntfs_mapping_pairs_decompress() in current ntfs code?
NTFS: Fix handling of valid but empty mapping pairs array in fs/ntfs/runlist.c::ntfs_mapping_pairs_decompress().
Signed-off-by: Anton Altaparmakov aia21@cantab.net
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/fs...
Best regards,
Anton
I haven't checked if this patch fix the problem. Xu, Can you check it ?
diff --git a/fs/ntfs/runlist.c b/fs/ntfs/runlist.c index 97932fb5179c..31263fe0772f 100644 --- a/fs/ntfs/runlist.c +++ b/fs/ntfs/runlist.c @@ -766,8 +766,11 @@ runlist_element *ntfs_mapping_pairs_decompress(const ntfs_volume *vol, return ERR_PTR(-EIO); } /* If the mapping pairs array is valid but empty, nothing to do. */
- if (!vcn && !*buf)
- if (!vcn && !*buf) {
- if (!old_rl)
- return ERR_PTR(-EIO);
return old_rl;
- }
/* Current position in runlist array. */ rlpos = 0; /* Allocate first page and set current runlist size to one page. */
- Eric