fix(psd): avoid signed overflow computing layer/mask extents#5306
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lgritz wants to merge 1 commit into
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fix(psd): avoid signed overflow computing layer/mask extents#5306lgritz wants to merge 1 commit into
lgritz wants to merge 1 commit into
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read_layer_record computed a layer's width/height as std::abs((int)right - (int)left). The rectangle coordinates are signed 32-bit values (layers can have negative offsets), but were stored in unsigned (uint32_t) struct fields, and subtracting two ints near the extremes overflows -- undefined behavior that UBSan flagged on a fuzzed file (1615681375 - -1605526113 cannot be represented in type 'int'). Retype Layer's and MaskData's top/left/bottom/right fields as int32_t, matching what they actually hold, instead of reinterpreting bits at the point of use. Widen to int64_t before subtracting so the computation can't overflow; the absolute difference of two int32 values always fits in uint32, and validate_resolution still rejects implausibly large extents. The mask data rect (used for layer masks) had the identical std::abs((int)right - (int)left) overflow hazard in load_layer_channel and gets the same fix. Assisted-by: Claude Code / Sonnet 5 Signed-off-by: Larry Gritz <lg@larrygritz.com>
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read_layer_record computed a layer's width/height as std::abs((int)right - (int)left). The rectangle coordinates are signed 32-bit values (layers can have negative offsets), but were stored in unsigned (uint32_t) struct fields, and subtracting two ints near the extremes overflows -- undefined behavior that UBSan flagged on a fuzzed file (1615681375 - -1605526113 cannot be represented in type 'int').
Retype Layer's and MaskData's top/left/bottom/right fields as int32_t, matching what they actually hold, instead of reinterpreting bits at the point of use. Widen to int64_t before subtracting so the computation can't overflow; the absolute difference of two int32 values always fits in uint32, and validate_resolution still rejects implausibly large extents.
The mask data rect (used for layer masks) had the identical std::abs((int)right - (int)left) overflow hazard in load_layer_channel and gets the same fix.
Assisted-by: Claude Code / Sonnet 5