stream_decoder: fix integer underflow due to malformed wasted_bits
It is pretty easy for a malformed FLAC file to underflow the "bps"
variable. In the debug build, this results in an assertion failure in
FLAC__bitreader_read_raw_uint32():
FLAC__ASSERT(bits <= 32);
In non-debug builds, this simply makes
FLAC__bitreader_read_raw_uint32() fail because
bitreader_read_from_client_() doesn't find enough buffer space for
2**32-1 bits. But since the failing FLAC_ASSERT() is reasonable, this
should be caught in the FLAC__bitreader_read_raw_uint32() caller.
Signed-off-by: Erik de Castro Lopo <erikd@mega-nerd.com>
Closes: https://github.com/xiph/flac/pull/13
diff --git a/src/libFLAC/stream_decoder.c b/src/libFLAC/stream_decoder.c
index fa0ef2c..c3a903f 100644
--- a/src/libFLAC/stream_decoder.c
+++ b/src/libFLAC/stream_decoder.c
@@ -2481,6 +2481,8 @@
if(!FLAC__bitreader_read_unary_unsigned(decoder->private_->input, &u))
return false; /* read_callback_ sets the state for us */
decoder->private_->frame.subframes[channel].wasted_bits = u+1;
+ if (decoder->private_->frame.subframes[channel].wasted_bits >= bps)
+ return false;
bps -= decoder->private_->frame.subframes[channel].wasted_bits;
}
else