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Fix integer overflow - #201
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pennam wants to merge 3 commits into
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Chunk size is accumulated from hex digits with no bounds check, so a long enough size overflows iChunkLength (int) - UB, yielding a bogus/negative length. Guard the accumulation with an INT_MAX pre-check so it can never overflow.
read() decremented iChunkLength unconditionally; if it hit 0 mid-chunk it went negative (UB at INT_MIN). Only decrement while it is still positive.
The old guard computed value*10+digit first, then checked for wrap-around - but that computation is itself UB and the check may be optimised away. Use a LONG_MAX pre-check so the overflow never happens.
Memory usage change @ c762f8d
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| iChunkLength = (iChunkLength * 16) + strtol(digit, NULL, 16); | ||
| // Only apply if the value fits in int without overflow. | ||
| if (iChunkLength <= ((INT_MAX - digitValue) / 16)) { |
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This is equivalent, but I think it may be easier to read
Suggested change
| if (iChunkLength <= ((INT_MAX - digitValue) / 16)) { | |
| if ((iChunkLength * 16) + digitValue <= INT_MAX) { |
| iContentLength = _iContentLength; | ||
| int digitValue = c - '0'; | ||
| // Only apply if the value fits in long without overflow. | ||
| if (iContentLength <= ((LONG_MAX - digitValue) / 10)) { |
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This is equivalent, but I think it may be easier to read
Suggested change
| if (iContentLength <= ((LONG_MAX - digitValue) / 10)) { | |
| if ((iContentLength * 10) + digitValue <= LONG_MAX) { |
andreagilardoni
approved these changes
Jul 13, 2026
rhpco
approved these changes
Jul 16, 2026
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Chunk size is accumulated from hex digits with no bounds check, so a long
enough size overflows iChunkLength (int) - UB, yielding a bogus/negative
length. Guard the accumulation with an INT_MAX pre-check so it can never
overflow.