refactor: make memmove vs memcpy behavior clearer #4447
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camshaft
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Mar 4, 2024
lrstewart
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camshaft
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Mar 4, 2024
maddeleine
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Mar 6, 2024
| @@ -15,7 +15,7 @@ | |||
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| #include "utils/s2n_safety.h" | |||
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| void *s2n_ensure_memcpy_trace(void *restrict to, const void *restrict from, size_t size) | |||
| void *s2n_ensure_memmove_trace(void *to, const void *from, size_t size) | |||
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Is there a reason why this function is called _trace?
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History: https://github.com/aws/s2n-tls/blame/9014236e7ba83869251298341264ccf1a37cd9f6/utils/s2n_ensure.c#L18-L24 Looks like it used to manually set the debug string.
But now the only work it really does is to check the result of memmove. The higher level macros could probably just do that themselves.
I opened an issue to remove it: #4457 I'd still like to merge this, as it's a step in the right direction.
maddeleine
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Mar 12, 2024
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Description of changes:
6648c66 switched us from using memcpy to memmove, but didn't remove the "restrict" keywords on the arguments. This can cause analysis tools like asan and valgrind to flag arguments with overlapping memory.
This PR removes the keywords, and also switches the definition of the safety macros to specify "memmove" instead of "memcpy" to reduce confusion.
However, I do NOT change the actual names of the safety macros, so most of our code will still use RESULT_CHECKED_MEMCPY or POSIX_CHECKED_MEMCPY. But now the fact that those macros use memmove instead is clear from their definitions, rather than requiring digging through several more layers. We can always change the safety macro names in a later PR, but I'm not sure it's necessary.
Testing:
There should be no behavior change, and existing tests pass.
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.