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LibGfx/OpenType: Ensure offsets are strictly less than the file size

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Previously, an offset that was equal to the size of the file would
cause a crash.
This commit is contained in:
Tim Ledbetter 2023-10-29 12:02:32 +00:00 • committed by Andreas Kling
parent 49d21619d4
commit a6f9ad6012
1 changed files with 3 additions and 3 deletions
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6
Userland/Libraries/LibGfx/Font/OpenType/Font.cpp
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@ -387,7 +387,7 @@ ErrorOr<NonnullRefPtr<Font>> Font::try_load_from_offset(ReadonlyBytes buffer, u3
if (Checked<u32>::addition_would_overflow(offset, (u32)Sizes::OffsetTable)) if (Checked<u32>::addition_would_overflow(offset, (u32)Sizes::OffsetTable))
return Error::from_string_literal("Invalid offset in font header"); return Error::from_string_literal("Invalid offset in font header");
if (buffer.size() < offset + (u32)Sizes::OffsetTable) if (buffer.size() <= offset + (u32)Sizes::OffsetTable)
return Error::from_string_literal("Font file too small"); return Error::from_string_literal("Font file too small");
Optional<ReadonlyBytes> opt_head_slice = {}; Optional<ReadonlyBytes> opt_head_slice = {};
@ -418,7 +418,7 @@ ErrorOr<NonnullRefPtr<Font>> Font::try_load_from_offset(ReadonlyBytes buffer, u3
Optional<GPOS> gpos; Optional<GPOS> gpos;
auto num_tables = be_u16(buffer.offset(offset + (u32)Offsets::NumTables)); auto num_tables = be_u16(buffer.offset(offset + (u32)Offsets::NumTables));
if (buffer.size() < offset + (u32)Sizes::OffsetTable + num_tables * (u32)Sizes::TableRecord) if (buffer.size() <= offset + (u32)Sizes::OffsetTable + num_tables * (u32)Sizes::TableRecord)
return Error::from_string_literal("Font file too small"); return Error::from_string_literal("Font file too small");
for (auto i = 0; i < num_tables; i++) { for (auto i = 0; i < num_tables; i++) {
@ -427,7 +427,7 @@ ErrorOr<NonnullRefPtr<Font>> Font::try_load_from_offset(ReadonlyBytes buffer, u3
u32 table_offset = be_u32(buffer.offset(record_offset + (u32)Offsets::TableRecord_Offset)); u32 table_offset = be_u32(buffer.offset(record_offset + (u32)Offsets::TableRecord_Offset));
u32 table_length = be_u32(buffer.offset(record_offset + (u32)Offsets::TableRecord_Length)); u32 table_length = be_u32(buffer.offset(record_offset + (u32)Offsets::TableRecord_Length));
if (Checked<u32>::addition_would_overflow(table_offset, table_length)) if (table_length == 0 || Checked<u32>::addition_would_overflow(table_offset, table_length))
return Error::from_string_literal("Invalid table offset or length in font"); return Error::from_string_literal("Invalid table offset or length in font");
if (buffer.size() < table_offset + table_length) if (buffer.size() < table_offset + table_length)