get_ue_golomb_31() reads nine bits and an array with 512 entries to
parse golomb codes. The longest golomb codes that fit into 9 bits use
four leading zeroes and five value bits and can encode numbers in the
0..30 range. 31 meanwhile is encoded on 11 bits and if the nine bits
read coincide with the first nine bits of the encoding of 31,
get_ue_golomb_31() returns 31 (and skips 11 bits).
But looking at the first nine bits only makes it impossible to distinguish
31 from 32..34. Therefore the documentation of get_ue_golomb_31() simply
states that the return value is undefined if the value of the encountered
exp golomb code was outside the 0..31 range.
But actually get_ue_golomb_31() does not behave that bad: If the returned
value is in the range of 0..30, then this is the actually encountered value,
so that this function can be used without any problems to parse and validate
parameters whose legal values are a subset of the 0..30 range.
This commit documents this fact.
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
This happened in get_ue_golomb() if the cached bitstream reader was in
use, because there was no check to handle the case of the read value
not being in the supported range.
For consistency with the uncached bitstream reader and for compliance
with the documentation, every value not in the 0-8190 range is treated as
error although the cached bitstream reader could actually read values in
the range 0..65534 without problems.
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Said error message is not very informative and lacked a proper logging
context; furthermore, many callers already provided more descriptive
error messages of their own. So just drop this one.
Suggested-by: James Almer <jamrial@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
add set_ue_golomb_long to support up to 2^32-2.
Reviewed-by: Mark Thompson <sw@jkqxz.net>
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Jun Zhao <jun.zhao@intel.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
set_ue_golomb just support 2^16 - 2 at most, becase this function call
put_bits, and put_bits just support write up to 31 bits, when write 32
bit in put_bits, it's will overwrite the bit buffer, and the default
assert level is 0, the av_assert2(n <= 31 && value < (1U << n)) in
put_bits can not be trigger runtime.
Signed-off-by: Jun Zhao <jun.zhao@intel.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Fixes slow loops on fuzzed data
Fixes: 245/fuzz-3-ffmpeg_AUDIO_AV_CODEC_ID_FLAC_fuzzer
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
get_ue_golomb() cannot decode values larger than 8190 (the maximum
value that can be golomb encoded in 25 bits) and produces the error
"Invalid UE golomb code" if a larger value is encountered. Use
get_ue_golomb_long() instead (which supports 63 bits, up to 4294967294)
when valid h264/hevc values can exceed 8190.
This updates decoding of the following values: (maximum)
first_mb_in_slice 36863* for level 5.2
abs_diff_pic_num_minus1 131071
difference_of_pic_nums_minus1 131071
idr_pic_id 65535
recovery_frame_cnt 65535
frame_packing_arrangement_id 4294967294
frame_packing_arrangement_repetition_period 16384
display_orientation_repetition_period 16384
An alternative would be to modify get_ue_golomb() to handle encoded
values of up to 49 bits as was done for get_se_golomb() in a92816c.
In that case get_ue_golomb() could continue to be used for all of
these except frame_packing_arrangement_id.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Also correct the check to reject log < 7, because UPDATE_CACHE only
guarantees 25 meaningful bits.
This fixes undefined behavior:
runtime error: shift exponent is negative
Testing with START/STOP timers in get_ue_golomb, one for the first
branch (A) and one for the second (B), shows that there is practically no
slowdown, e.g. for the cavs decoder:
With the check in the B branch:
629 decicycles in get_ue_golomb B, 4194260 runs, 44 skips
433 decicycles in get_ue_golomb A,268434102 runs, 1354 skips
Without the check:
624 decicycles in get_ue_golomb B, 4194273 runs, 31 skips
433 decicycles in get_ue_golomb A,268434203 runs, 1253 skips
Since the B branch is executed far less often than the A branch, this
change is negligible, even more so for the h264 decoder, where the ratio
B/A is a lot smaller.
Fixes: mozilla bug 1230239
Fixes: fbeb8b2c7c996e9b91c6b1af319d7ebc/asan_heap-oob_195450f_2743_e8856ece4579ea486670be2b236099a0.bit
Found-by: Tyson Smith
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
This was only used in hevc muxing code so far.
This makes the return values match what get_se_golomb returns for
the same bitstream reader instances.
The logic for producing a signed golomb code out of an unsigned one
was based on the corresponding code in get_se_golomb, which operated
directly on the bitstream reader buffer - not on the equivalent
return value from get_ue_golomb.
CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>
* qatar/master:
golomb: use unsigned arithmetics in svq3_get_ue_golomb()
x86: float_dsp: fix loading of the len parameter on x86-32
takdec: fix initialisation of LOCAL_ALIGNED array
takdec: fix initialisation of LOCAL_ALIGNED array
Conflicts:
libavcodec/rv30.c
libavcodec/svq3.c
libavcodec/takdec.c
Merged-by: Michael Niedermayer <michaelni@gmx.at>
This prevents undefined behaviour of signed left shift if the coded
value is larger than 2^31. Large values are most likely invalid and
caused errors or by feeding random.
Validate every use of svq3_get_ue_golomb() and changed the place there
the return value was compared with negative numbers. dirac.c was clean,
fixed rv30 and svq3.
* qatar/master:
libopus: Remap channels using libopus' internal remapping.
Opus decoder using libopus
avcodec: document the use of AVCodecContext.delay for audio decoding
vc1dec: add flush function for WMV9 and VC-1 decoders
http: Increase buffer sizes to cope with longer URIs
nutenc: const correctness for ff_put_v_trace/put_s_trace function arguments
h264_refs: Fix debug tprintf argument types
golomb: const correctness for get_ue()/get_se() function arguments
get_bits: const correctness for get_bits_trace()/get_xbits_trace() arguments
Conflicts:
Changelog
libavcodec/Makefile
libavcodec/version.h
libavformat/http.c
Merged-by: Michael Niedermayer <michaelni@gmx.at>
