Stricter rules when parsing time values to avoid UBSAN error#3148
Stricter rules when parsing time values to avoid UBSAN error#3148kevinbackhouse merged 2 commits intoExiv2:mainfrom
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Stricter rules when parsing time values to avoid UBSAN error.
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@Mergifyio backport 0.28.x |
✅ Backports have been createdDetails
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| // Basic format | ||
| auto tzhi = std::stoi(format.substr(0, posColon)); | ||
| if (tzhi > 23) | ||
| if (tzhi < -23 || tzhi > 23) |
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Could limit this (and one above) even more from -12 to 14 strictly speaking, but I guess this is just to keep the fuzzer from going to crazy...
Stricter rules when parsing time values to avoid UBSAN error (backport #3148)
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@kevinbackhouse woun't it be better to use strtoul for some of these? |
I don't think that would help, because they get written into a struct with Lines 1003 to 1009 in b917b34 |
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So a cast would turn negatives to 0? |
What I mean is: if we use Of course these integer overflows are completely harmless, and they don't happen on legitimate image files, so this PR is purely about silencing an irrelevant UBSAN error. |
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This fixes a UBSAN error found by OSS-Fuzz: https://issues.oss-fuzz.com/issues/392928817
The error message is:
It happens here:
exiv2/src/value.cpp
Line 975 in 3b58bda
The integer overflow is harmless, but I have fixed it by making the parsing rules stricter.