[FFmpeg-devel] [PATCH] avcodec/tiff: Check for Tiled and Stripped TIFFs

[James Almer]

On 2/27/2020 11:10 AM, Carl Eugen Hoyos wrote:
> Am Do., 27. Feb. 2020 um 15:05 Uhr schrieb Anton Khirnov <anton at khirnov.net>:
>>
>> Quoting Michael Niedermayer (2020-02-19 16:49:51)
>>> TIFF 6 spec: "Do not use both strip-oriented and tile-oriented fields in the same TIFF file."
>>>
>>> Fixes: null pointer use, crash
>>> Fixes: crash-762680f9d1b27f9b9085e12887ad44893fb2b020
>>>
>>> Found-by: Shiziru <lunasl at protonmail.com>
>>> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
>>> ---
>>>  libavcodec/tiff.c | 6 ++++++
>>>  1 file changed, 6 insertions(+)
>>>
>>> diff --git a/libavcodec/tiff.c b/libavcodec/tiff.c
>>> index e8357114de..fd50b1cbfa 100644
>>> --- a/libavcodec/tiff.c
>>> +++ b/libavcodec/tiff.c
>>> @@ -1873,6 +1873,12 @@ again:
>>>          return AVERROR_INVALIDDATA;
>>>      }
>>>
>>> +    if (   (s->is_tiled || s->tile_byte_counts_offset || s->tile_offsets_offset || s->tile_width || s->tile_length || s->tile_count)
>>> +        && (s->strippos || s->strips || s->stripoff || s->rps || s->sot || s->sstype || s->stripsize || s->stripsizesoff)) {
>>
>> This is horribly unreadable. Putting those checks into macros, like
>> HAVE_TILES(s) and HAVE_STRIPS(s) would make it a lot better.
> 
> Were else in the file could the macros be used?
> I fear that adding macros that are only used in one place will make the
> code much more unreadable.

I don't agree. An "if (HAVE_TILES(s) && HAVE_STRIPS(s))" check is easy
to understand at first glance, regardless of the internals of each of
those macros. It achieves the same effect as adding a comment in the
code to explain what all those checks do.

See IS_IRAP_NAL(nal) and IS_IDR_NAL(nal) in hevc_parser for another
example of this simplification, which are also used in a single place.

> 
> Carl Eugen
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