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Differential D52854

lib{c,openbsd}: use ckd_mul() for overflow checking in re(c)allocarray
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Authored by fuz on Oct 2 2025, 1:30 PM.
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kib
imp
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rG7233893e9496: lib{c,openbsd}: use ckd_mul() for overflow checking in re(c)allocarray
Summary

This makes the code easier to understand and slightly faster,
but requires C23. calloc() would benefit, too, but I didn't
want to touch the imported jemalloc code base.

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rG FreeBSD src repository
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Event Timeline

fuz requested review of this revision.Oct 2 2025, 1:30 PM
fuz created this revision.
Harbormaster completed remote builds in B67487: Diff 163342.Oct 2 2025, 1:30 PM
fuz added a child revision: D52863: lib/libc: add recallocarray().Oct 2 2025, 4:26 PM
kib accepted this revision.Oct 2 2025, 11:00 PM
kib added inline comments.
lib/libopenbsd/recallocarray.c
36

I would wrote

if (ckd_mul(&newsize, newnmemb, size) ||
    ckd_mul(&oldsize, oldnmemb, size)) {
             errno = EINVAL;
             return NULL;
}

since there are much simpler conditions now.

This revision is now accepted and ready to land.Oct 2 2025, 11:00 PM
fuz added inline comments.Oct 3 2025, 1:42 AM
lib/libopenbsd/recallocarray.c
36

This cannot be done as one needs to fail with ENOMEM while the other fails with EINVAL.

kib added inline comments.Oct 3 2025, 5:35 PM
lib/libopenbsd/recallocarray.c
36

Indeed, missed that.

Closed by commit rG7233893e9496: lib{c,openbsd}: use ckd_mul() for overflow checking in re(c)allocarray (authored by fuz). · Explain WhyOct 3 2025, 5:48 PM
This revision was automatically updated to reflect the committed changes.
fuz added a commit: rG7233893e9496: lib{c,openbsd}: use ckd_mul() for overflow checking in re(c)allocarray.

Revision Contents
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PathSize
lib/
libc/
stdlib/
14 lines
libopenbsd/
15 lines

Diff 163472

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lib/libc/stdlib/reallocarray.c

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lib/libopenbsd/recallocarray.c

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