зеркало из https://github.com/mozilla/gecko-dev.git
78 строки
2.2 KiB
Diff
78 строки
2.2 KiB
Diff
Bug 1050342. Fix a case where the fast huffman decoder in libjpeg-turbo can produce different results depending on how data is fed to it.
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This change comes from the blink repo https://codereview.appspot.com/229430043/ and is unlikely to be accepted upstream into libjpeg-turbo.
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diff --git jdhuff.c jdhuff.c
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--- jdhuff.c
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+++ jdhuff.c
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@@ -674,9 +674,9 @@ decode_mcu_fast(j_decompress_ptr cinfo,
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d_derived_tbl *dctbl = entropy->dc_cur_tbls[blkn];
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d_derived_tbl *actbl = entropy->ac_cur_tbls[blkn];
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register int s, k, r, l;
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- HUFF_DECODE_FAST(s, l, dctbl);
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+ HUFF_DECODE_FAST(s, l, dctbl, slow_decode_mcu);
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if (s) {
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FILL_BIT_BUFFER_FAST
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r = GET_BITS(s);
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s = HUFF_EXTEND(r, s);
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@@ -692,9 +692,9 @@ decode_mcu_fast(j_decompress_ptr cinfo,
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if (entropy->ac_needed[blkn] && block) {
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for (k = 1; k < DCTSIZE2; k++) {
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- HUFF_DECODE_FAST(s, l, actbl);
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+ HUFF_DECODE_FAST(s, l, actbl, slow_decode_mcu);
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r = s >> 4;
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s &= 15;
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if (s) {
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@@ -711,9 +711,9 @@ decode_mcu_fast(j_decompress_ptr cinfo,
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} else {
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for (k = 1; k < DCTSIZE2; k++) {
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- HUFF_DECODE_FAST(s, l, actbl);
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+ HUFF_DECODE_FAST(s, l, actbl, slow_decode_mcu);
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r = s >> 4;
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s &= 15;
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if (s) {
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@@ -728,8 +728,9 @@ decode_mcu_fast(j_decompress_ptr cinfo,
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}
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}
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if (cinfo->unread_marker != 0) {
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+slow_decode_mcu:
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cinfo->unread_marker = 0;
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return FALSE;
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}
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diff --git jdhuff.h jdhuff.h
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--- jdhuff.h
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+++ jdhuff.h
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@@ -210,9 +210,9 @@ slowlabel: \
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get_buffer = state.get_buffer; bits_left = state.bits_left; \
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} \
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}
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-#define HUFF_DECODE_FAST(s, nb, htbl) \
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+#define HUFF_DECODE_FAST(s, nb, htbl, slowlabel) \
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FILL_BIT_BUFFER_FAST; \
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s = PEEK_BITS(HUFF_LOOKAHEAD); \
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s = htbl->lookup[s]; \
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nb = s >> HUFF_LOOKAHEAD; \
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@@ -227,9 +227,11 @@ slowlabel: \
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s <<= 1; \
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s |= GET_BITS(1); \
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nb++; \
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} \
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- s = htbl->pub->huffval[(int)(s + htbl->valoffset[nb]) & 0xFF]; \
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+ if (nb > 16) \
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+ goto slowlabel; \
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+ s = htbl->pub->huffval[ (int) (s + htbl->valoffset[nb]) ]; \
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}
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/* Out-of-line case for Huffman code fetching */
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EXTERN(int) jpeg_huff_decode(bitread_working_state *state,
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