33 lines
1.2 KiB
Diff
33 lines
1.2 KiB
Diff
Subject: [PATCH] Read unaligned match buffers with memcpy
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Byte buffers need not satisfy integer alignment or aliasing requirements.
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GCC 16 with x86-64-v3 vectorizes the cast loads using aligned AVX reads,
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causing a segmentation fault. Copy into local integers instead.
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--- a/src/zopfli/lz77.c
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+++ b/src/zopfli/lz77.c
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@@ -302,13 +302,20 @@
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if (sizeof(size_t) == 8) {
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/* 8 checks at once per array bounds check (size_t is 64-bit). */
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- while (scan < safe_end && *((size_t*)scan) == *((size_t*)match)) {
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+ while (scan < safe_end) {
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+ size_t scan_word, match_word;
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+ memcpy(&scan_word, scan, sizeof(scan_word));
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+ memcpy(&match_word, match, sizeof(match_word));
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+ if (scan_word != match_word) break;
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scan += 8;
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match += 8;
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}
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} else if (sizeof(unsigned int) == 4) {
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/* 4 checks at once per array bounds check (unsigned int is 32-bit). */
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- while (scan < safe_end
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- && *((unsigned int*)scan) == *((unsigned int*)match)) {
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+ while (scan < safe_end) {
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+ unsigned int scan_word, match_word;
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+ memcpy(&scan_word, scan, sizeof(scan_word));
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+ memcpy(&match_word, match, sizeof(match_word));
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+ if (scan_word != match_word) break;
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scan += 4;
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match += 4;
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}
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