decode_tsd() computes the binomial coefficient c = C(k, p) incrementally.
this commit makes it less overflow prone
Fixes: 515703905/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AAC_DEC_fuzzer-4890954254581760
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Later code will turn this into AVERROR_BUG
When returning sample_rate == 0 samples is considered a bug, we have no
nice choice but to error out cleanly
Fixes: assertion failure
Fixes: ffmpeg_AV_CODEC_ID_AAC_DEC_fuzzer crash-0a86d46fef2442b222ee34403c21f7f582ffccb0
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This also reverts: c2364e9222
Fixes: out of array access (testcase exists but did not replicate for me)
Founbd-by: Gil Portnoy <dddhkts1@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
`spectrum_decode` currently executes Frequency Domain (FD) decoding steps
for all channels, regardless of their `core_mode`. When a channel is in
Linear Prediction Domain (LPD) mode (`core_mode == 1`), FD-specific
parameters such as scalefactor offsets (`sfo`) and individual channel
stream (`ics`) information are not parsed.
This causes a global-buffer-overflow in `dequant_scalefactors`. Because
`spectrum_scale` is called on LPD channels, it uses stale or
uninitialized `sfo` values to index `ff_aac_pow2sf_tab`. In the reported
crash, a stale `sfo` value of 240 resulted in an index of 440
(240 + POW_SF2_ZERO), exceeding the table's size of 428.
Fix this by ensuring `spectrum_scale` and `imdct_and_windowing` are only
called for channels where `core_mode == 0` (FD).
Co-authored-by: CodeMender <codemender-patching@google.com>
Fixes: https://issues.oss-fuzz.com/486160985
Without the specification, limiting the index is the best that can be done.
Fixes: out of array access
Fixes: 487591441/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AAC_LATM_fuzzer-6205915698364416
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Fixes: left shift of negative value -2
Fixes: 487591441/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AAC_LATM_fuzzer-6205915698364416
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
fix a simple index bug in ff_aac_usac_reset_state()
that writes past the end of ChannelElement.ch[2] for CPE
ff_aac_usac_reset_state() loops over channels with j < ch, but
incorrectly takes &che->ch[ch]. For CPE (ch == 2) this becomes
che->ch[2], which is one past the end of ChannelElement.ch[2], and the
subsequent memset() causes an intra-object out-of-bounds write.
index the channel element with the loop variable (j).
A heap-use-after-free vulnerability was identified in
`libavcodec/aac/aacdec.c`. When `che_configure` frees a
`ChannelElement` (`ac->che[type][id]`), it failed to clear all
references to it in `ac->tag_che_map`. `ac->tag_che_map` caches
pointers to `ChannelElement`s and can contain cross-type mappings (e.g.,
a `TYPE_SCE` tag mapping to a `TYPE_LFE` element).
In a USAC stream reconfiguration scenario, an LFE element was freed, but
a stale pointer remained in `ac->tag_che_map`. Subsequent calls to
`ff_aac_get_che` returned this dangling pointer, leading to a crash in
`decode_usac_core_coder`.
This commit fixes the issue by iterating over the entire
`ac->tag_che_map` in `che_configure` and clearing any entries that point
to the `ChannelElement` about to be freed, ensuring no dangling pointers
remain.
Fixes: https://issues.oss-fuzz.com/issues/440220467
Extensions in AAC USAC can be stored across multiple frames (mainly to keep CBR compliance).
This means that we need to reallocate a buffer when new data is received, accumulate the bitstream data,
and so on until the end of extension flag is signalled and the extension can be decoded.
This is made more complicated by the way in which the AAC channel layout switching is performed.
After decades of evolution, our AAC decoder evolved to double-buffer its entire configuration.
All changes are buffered, verified, and applied, on a per-frame basis if required, in often
random order.
Since we allocate the extension data on heap, this means that if configuration is applied,
in order to avoid double-freeing, we have to keep track of what we've allocated.
It should be noted that extensions which are spread in multiple frames are generally rare,
so an optimization to introduce av_refstruct_realloc() wouldn't generally be useful across the codebase.
Therefore, a copy is good enough for now.
Thanks to Michael Niedermayer for additional fixing.
Fixes: double free
Fixes: 393523547/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AAC_LATM_fuzzer-6740617236905984
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Fixes: out of array read
Fixes: 397731127/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AAC_LATM_fuzzer-5577772965101568
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
The issue is that state->cur[] is 8-bits, but a+b+1 can overflow
before being clipped to 0xF in the following line, causing an incorrect
state to be saved for the next symbol.
This solves numerous bitstream desyncs, particularly when coefficients
with magnitude greater than 127 are sent.
The aim of this is twofold: a) Clang warns when setting a deprecated
field in a definition and because several of the widely set
AVCodec fields are deprecated, one gets several hundred warnings
from Clang for an ordinary build. Yet fortunately Clang (unlike GCC)
allows to disable deprecation warnings inside a definition, so
that one can create simple macros to set these fields that also suppress
deprecation warnings for Clang. This has already been done in
fdff1b9cbf for AVCodec.channel_layouts.
b) Using macros will allow to easily migrate these fields to internal ones.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
It's not possible to put USAC into ADTS due to exceeding the
field size (4 bits) for ADTS profile. As such cases where
the frame starts with 0xfff shouldn't be checked.
This ensures the sample at https://crbug.com/396190942 is
properly detected as USAC content.
Signed-off-by: Dale Curtis <dalecurtis@chromium.org>
The limit is based on later code storing 32bits
Fixes: signed integer overflow: 2147483647 + 1 cannot be represented in type 'int'
Fixes: 393164866/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AAC_LATM_fuzzer-4606798354513920
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
types and SFO become confused for a USAC stream
Fixes: out of array access
Fixes: 383854203/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AAC_LATM_fuzzer-4996677847547904.fuzz
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
