lkml.org 
[lkml]   [2022]   [Jun]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2] fs/ntfs: fix BUG_ON of ntfs_read_block()
On Fri, Jun 24, 2022 at 11:33:28AM +0900, Namjae Jeon wrote:
> 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 Xuexin<jiang.xuexin@zte.com.cn>
> >> Reviewed-by: Zhang wenya<zhang.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 ?
>

I have test it and it fixes the problem.

Thanks.

> 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
> >

\
 
 \ /
  Last update: 2022-06-24 05:56    [W:0.101 / U:0.660 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site