Module Name: src
Committed By: riastradh
Date: Fri Mar 28 19:13:23 UTC 2025
Modified Files:
src/lib/libc/locale: rune.c
src/tests/lib/libc/gen: t_ctype.c
Log Message:
libc: Put guard pages before locale ctype/tolower/toupper tables.
This way, triggering the undefined behaviour of negative inputs to
the ctype functions leads to instant SIGSEGV, rather than silently
giving bonkers (and likely nondeterministic) answers. (See ctype(3)
man page for details.)
This only affects non-default locales, i.e., locales other than C.
The C locale's tables are statically linked into libc, and the
symbols defining them are baked into the ABI, so putting a guard page
before them will require either some careful elven surgery (which is
a class I must have missed back in university), or copying them into
dynamically allocated memory (which is a cost I'm reluctant to incur
on all programs using libc).
This also only affects machines where char is signed for now. (But
maybe it would be worth doing unconditionally; users could still try
to pass in explicit `signed char' inputs.)
PR lib/58208: ctype(3) provides poor runtime feedback of abuse
To generate a diff of this commit:
cvs rdiff -u -r1.47 -r1.48 src/lib/libc/locale/rune.c
cvs rdiff -u -r1.2 -r1.3 src/tests/lib/libc/gen/t_ctype.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
