Daniel Bertalan 78e7ff008b LibC: Fix negation overflow UB in sys/mman.cpp ...

When the system calls return `NumericLimits<ptrdiff_t>::min()`, negating
the return code would produce `NumericLimits<ptrdiff_t>::max() + 1`
since we are on a two's complement architecture. Because this value
cannot be stored, signed overflow occurs which is UB. This can be fixed
by applying the negation to `EMAXERRNO` since that's known to contain a
relatively small value.

Found when running tests with Clang.

2021-08-08 10:55:36 +02:00

2.4 KiB

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