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Fix heap buffer overflow in libopenapv encoder #212

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Fix heap buffer overflow in libopenapv encoder #212

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1 change: 1 addition & 0 deletions src/oapv.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1171,6 +1171,7 @@ static int enc_frame(oapve_ctx_t *ctx, oapv_bs_t *bs)
/****************************************************/

for(int i = 0; i < ctx->num_tiles; i++) {
oapv_assert_gv(bs_tile_pos + ctx->tile[i].bs_size <= bs->end, ret, OAPV_ERR_OUT_OF_BS_BUF, ERR);

@kpchoi kpchoi Jun 16, 2026

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this function is for encoding process, so that the tile[i].bs_size has correct number.
If the address is located in outside of available bitstream buffer, enc_tile() returns error.

@fkyslov fkyslov Jun 16, 2026

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the check at enc_tile() happens after enc_tile_comp where the buffer overrun can happen.

@fkyslov fkyslov Jun 16, 2026

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Also, each individual tile buffer (tile[i].bs_size) may be fit, but when assembling all encoded tiles into common "bs" we need to check if the sum of tiles doesn't exceed the common "bs" size. I.e. those are different checks.

@kpchoi kpchoi Jun 17, 2026

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LGTM

oapv_mcpy(bs_tile_pos, ctx->tile[i].bs_buf, ctx->tile[i].bs_size);
bs_tile_pos = bs_tile_pos + ctx->tile[i].bs_size;
ctx->fh.tile_size[i] = ctx->tile[i].bs_size - OAPV_TILE_SIZE_LEN;
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32 changes: 20 additions & 12 deletions src/oapv_vlc.c
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Expand Up @@ -37,23 +37,31 @@
#if ENABLE_ENCODER
///////////////////////////////////////////////////////////////////////////////
#define BSW_FLUSH_4BYTE(bs) { \

@kpchoi kpchoi Jun 16, 2026

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This function is called anywhere. It will be removed.

*(bs)->cur++ = ((bs)->code >> 24) & 0xFF; \
*(bs)->cur++ = ((bs)->code >> 16) & 0xFF; \
*(bs)->cur++ = ((bs)->code >> 8) & 0xFF; \
*(bs)->cur++ = ((bs)->code) & 0xFF; \
if ((bs)->cur + 4 <= (bs)->end) { \
*(bs)->cur++ = ((bs)->code >> 24) & 0xFF; \
*(bs)->cur++ = ((bs)->code >> 16) & 0xFF; \
*(bs)->cur++ = ((bs)->code >> 8) & 0xFF; \
*(bs)->cur++ = ((bs)->code) & 0xFF; \
} else { \
(bs)->cur += 4; \
} \
(bs)->code = 0; \
(bs)->leftbits = 32; \
}

#define BSW_FLUSH_8BYTE(bs) { \

@kpchoi kpchoi Jun 16, 2026

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This function is called anywhere. It will be removed

@fkyslov fkyslov Jun 16, 2026

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It is called in BSW_WRITE_64BITS and BSW_WRITE_64BITS is called in oapve_vlc_ac_coef and oapve_vlc_ac_coef is called in enc_tile_comp, or am I missing something?

@kpchoi kpchoi Jun 17, 2026

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Again, one branch in vlc loop code, it makes noticeable speed-down.
It is assumed that the input buffer should be allocated large enough.
This code should be reconsidered.

@kpchoi kpchoi Jun 25, 2026

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I'd like to suggest to merge this PR without BSW_WRITE_XX changes.
I think we can reconsider BSW_WRITE_XX code changes if some noticeable issue occurs.

*(bs)->cur++ = ((bs)->code >> 56) & 0xFF; \
*(bs)->cur++ = ((bs)->code >> 48) & 0xFF; \
*(bs)->cur++ = ((bs)->code >> 40) & 0xFF; \
*(bs)->cur++ = ((bs)->code >> 32) & 0xFF; \
*(bs)->cur++ = ((bs)->code >> 24) & 0xFF; \
*(bs)->cur++ = ((bs)->code >> 16) & 0xFF; \
*(bs)->cur++ = ((bs)->code >> 8) & 0xFF; \
*(bs)->cur++ = ((bs)->code) & 0xFF; \
if ((bs)->cur + 8 <= (bs)->end) { \
*(bs)->cur++ = ((bs)->code >> 56) & 0xFF; \
*(bs)->cur++ = ((bs)->code >> 48) & 0xFF; \
*(bs)->cur++ = ((bs)->code >> 40) & 0xFF; \
*(bs)->cur++ = ((bs)->code >> 32) & 0xFF; \
*(bs)->cur++ = ((bs)->code >> 24) & 0xFF; \
*(bs)->cur++ = ((bs)->code >> 16) & 0xFF; \
*(bs)->cur++ = ((bs)->code >> 8) & 0xFF; \
*(bs)->cur++ = ((bs)->code) & 0xFF; \
} else { \
(bs)->cur += 8; \
} \
(bs)->code = 0; \
(bs)->leftbits = 64; \
}
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