> On Feb 20, 2019, at 3:50 AM, Jan Kara <jack@xxxxxxx> wrote:
>
>> On Tue 19-02-19 08:17:09, Steve Magnani wrote:
>>> On 2/19/19 8:02 AM, Jan Kara wrote:
>>>> On Tue 19-02-19 11:44:03, Colin King wrote:
>>>> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>>>>
>>>> There is a null check on the pointer bh to avoid a null pointer dereference
>>>> on bh->b_data however later bh is passed to mark_buffer_dirty that can also
>>>> cause a null pointer dereference on bh. Avoid this potential null pointer
>>>> dereference by moving the call to mark_buffer_dirty inside the null checked
>>>> block.
>>>>
>>>> Fixes: e8b4274735e4 ("udf: finalize integrity descriptor before writeback")
>>>> Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>>> Thanks for the patch! In fact it is the 'if (bh)' check that's
>>> unnecessarily defensive (we cannot have sbi->s_lvid_dirty and
>>> !sbi->s_lvid_bh). So I'll just drop that check (attached patch).
>>>
>>> Honza
>>>
>>>> ---
>>>> fs/udf/super.c | 12 ++++++------
>>>> 1 file changed, 6 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/fs/udf/super.c b/fs/udf/super.c
>>>> index a6940d90bedd..b7e9a83d39db 100644
>>>> --- a/fs/udf/super.c
>>>> +++ b/fs/udf/super.c
>>>> @@ -2336,13 +2336,13 @@ static int udf_sync_fs(struct super_block *sb, int wait)
>>>> lvid = (struct logicalVolIntegrityDesc *)bh->b_data;
>>>> udf_finalize_lvid(lvid);
>>>> - }
>>>> - /*
>>>> - * Blockdevice will be synced later so we don't have to submit
>>>> - * the buffer for IO
>>>> - */
>>>> - mark_buffer_dirty(bh);
>>>> + /*
>>>> + * Blockdevice will be synced later so we don't have
>>>> + * to submit the buffer for IO
>>>> + */
>>>> + mark_buffer_dirty(bh);
>>>> + }
>>>> sbi->s_lvid_dirty = 0;
>>>> }
>>>> mutex_unlock(&sbi->s_alloc_mutex);
>>>> --
>>>> 2.20.1
>>>>
>> Reviewed-by: Steven J. Magnani <steve@xxxxxxxxxxxxxxx>
>
> Is this Reviewed-by for my fixup or the Colin's? Because I've decided to
> rather remove the 'if (bh)' check completely since it is pointless...
>
> Honza
> --
Sorry, I realized on rereading that this could be ambiguous. The R-B is for your patch.
Steve
