On Fri, Jun 24, 2022 at 11:33:28AM +0900, Namjae Jeon wrote: > 2022-06-24 2:08 GMT+09:00, Eric Biggers <ebiggers@xxxxxxxxxx>: > > On Thu, Jun 23, 2022 at 09:49:56AM +0000, cgel.zte@xxxxxxxxx wrote: > >> From: xu xin <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. > > 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 > >
