2022-06-24 2:08 GMT+09:00, Eric Biggers ebiggers@kernel.org:
On Thu, Jun 23, 2022 at 09:49:56AM +0000, cgel.zte@gmail.com wrote:
From: xu xin 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.
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