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Fix out-of-bounds reads in cmap format-12 and kern format-0 parsers #45

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Fix out-of-bounds reads in cmap format-12 and kern format-0 parsers #45

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6 changes: 6 additions & 0 deletions schrift.c
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Original file line number Diff line number Diff line change
Expand Up @@ -328,6 +328,8 @@ sft_kerning(const SFT *sft, SFT_Glyph leftGlyph, SFT_Glyph rightGlyph,
return -1;
numPairs = getu16(sft->font, offset);
offset += 8;
if (!is_safe_offset(sft->font, offset, (uint_fast32_t) numPairs * 6))
return -1;
/* Look up character code pair via binary search. */
key[0] = (leftGlyph >> 8) & 0xFF;
key[1] = leftGlyph & 0xFF;
Expand Down Expand Up @@ -866,6 +868,10 @@ cmap_fmt12_13(SFT_Font *font, uint_fast32_t table, SFT_UChar charCode, SFT_Glyph

numEntries = getu32(font, table + 12);

/* Ensure the declared number of groups fits within the subtable. */
if (numEntries > (len - 16) / 12)
return -1;

for (i = 0; i < numEntries; ++i) {
uint32_t firstCode, lastCode, glyphOffset;
firstCode = getu32(font, table + (i * 12) + 16);
Expand Down