Date: Fri, 24 Feb 2023 21:13:34 +0600 From: NRK <nrk@...root.org> To: Tamir Duberstein <tamird@...gle.com> Cc: Rich Felker <dalias@...c.org>, musl@...ts.openwall.com Subject: Re: undefined behavior in fread.c On Fri, Feb 24, 2023 at 09:42:00AM -0500, Tamir Duberstein wrote: > We could take the lock and still avoid UB with an early return. As Jens has pointed out, the UB in this case is the caller calling fread with NULL - not in musl. And on a sidenote, I've always found - especially for the various mem* functions - accepting 0 size but not accepting NULL arg (when n is 0) to be a poor choice. A lot of the value that accepting 0 size provides is diminished by not accepting NULL. And this affects more than just libc, too. Compilers like gcc/clang will see a call like `memcmp(p, q, 0)` and will ""determine"" `p` and `q` are non-null (which can lead to deleting any subsequent null-checks on those pointers). But anyways, that was just a small rant. As things currently are, *even if* musl deal with the NULL pointer - any caller calling fread with NULL is still in danger from compilers and needs to fix it on their side. - NRK
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