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 ? 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 >
