2022-06-24 21:19 GMT+09:00, Anton Altaparmakov <anton@xxxxxxxxxx>: > Hi, > > On 24 Jun 2022, at 03:33, Namjae Jeon > <linkinjeon@xxxxxxxxxx<mailto:linkinjeon@xxxxxxxxxx>> wrote: > > 2022-06-24 2:08 GMT+09:00, Eric Biggers > <ebiggers@xxxxxxxxxx<mailto:ebiggers@xxxxxxxxxx>>: > On Thu, Jun 23, 2022 at 09:49:56AM +0000, > cgel.zte@xxxxxxxxx<mailto:cgel.zte@xxxxxxxxx> wrote: > From: xu xin <xu.xin16@xxxxxxxxxx<mailto:xu.xin16@xxxxxxxxxx>> > > As the bug description at > https://lore.kernel.org/lkml/20220623033635.973929-1-xu.xin16@xxxxxxxxxx/ > 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@xxxxxxxxxxxxxxx > Reported-by: Zeal Robot <zealci@xxxxxxxxxx> > Reported-by: syzbot+6a5a7672f663cce8b156@xxxxxxxxxxxxxxxxxxxxxxxxx > Reviewed-by: Songyi Zhang <zhang.songyi@xxxxxxxxxx> > Reviewed-by: Yang Yang <yang.yang29@xxxxxxxxxx> > Reviewed-by: Jiang Xuexin<jiang.xuexin@xxxxxxxxxx> > Reviewed-by: Zhang wenya<zhang.wenya1@xxxxxxxxxx> > Signed-off-by: xu xin <xu.xin16@xxxxxxxxxx> > --- > > Change for v2: > - Use ntfs_warning instead of WARN(). > - Add the tag Cc: stable@xxxxxxxxxxxxxxx. > --- > 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@xxxxxxxxxx> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/fs/ntfs/runlist.c?h=v5.19-rc3&id=2b0ada2b8e086c267dd116a39ad41ff0a717b665 > > 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 > >
