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Code Issues Releases Activity

apv_entropy: Improve robustness to bitstream errors

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This commit is contained in:
Mark Thompson
2025-05-03 18:44:43 +01:00
parent 2aa2095bb4
commit ea457e54e1
1 changed files with 16 additions and 0 deletions
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16
libavcodec/apv_entropy.c
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@ -84,6 +84,14 @@ static unsigned int apv_read_vlc(GetBitContext *gbc, int k_param,
next_bits = show_bits(gbc, 16); next_bits = show_bits(gbc, 16);
leading_zeroes = 15 - av_log2(next_bits); leading_zeroes = 15 - av_log2(next_bits);
if (leading_zeroes == 0) {
// This can't happen mid-stream because the lookup would
// have resolved a leading one into a shorter code, but it
// can happen if we are hitting the end of the buffer.
// Return an invalid code to propagate as an error.
return APV_MAX_TRANS_COEFF + 1;
}
skip_bits(gbc, leading_zeroes + 1); skip_bits(gbc, leading_zeroes + 1);
return (2 << k_param) + return (2 << k_param) +
@ -182,6 +190,14 @@ int ff_apv_entropy_decode_block(int16_t *coeff,
else else
level = abs_ac_coeff_minus1 + 1; level = abs_ac_coeff_minus1 + 1;
if (level < APV_MIN_TRANS_COEFF ||
level > APV_MAX_TRANS_COEFF) {
av_log(state->log_ctx, AV_LOG_ERROR,
"Out-of-range AC coefficient value: %d "
"(from prev_level %d abs_ac_coeff_minus1 %d sign_ac_coeff %d)\n",
level, prev_level, abs_ac_coeff_minus1, sign_ac_coeff);
}
coeff[ff_zigzag_direct[scan_pos]] = level; coeff[ff_zigzag_direct[scan_pos]] = level;
prev_level = abs_ac_coeff_minus1 + 1; prev_level = abs_ac_coeff_minus1 + 1;