Messages in this thread | | | Date | Fri, 2 Feb 2024 02:41:55 -0800 | From | Kees Cook <> | Subject | Re: [PATCH] ubsan: Silence W=1 warnings in self-test |
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On Fri, Feb 02, 2024 at 10:57:11AM +0100, Marco Elver wrote: > On Fri, 2 Feb 2024 at 10:46, Kees Cook <keescook@chromium.org> wrote: > > > > Silence a handful of W=1 warnings in the UBSan selftest, which set > > variables without using them. For example: > > > > lib/test_ubsan.c:101:6: warning: variable 'val1' set but not used [-Wunused-but-set-variable] > > 101 | int val1 = 10; > > | ^ > > This is the shift_out_of_bounds test? It looks like the neg and wrap > variables are volatile but the written-to variables aren't. > Technically the compiler just has to emit the reads to neg and wrap, > and can entirely omit the writes to val1 and val2. > > Does making it volatile fix the warning?
It does for some, but not all:
./lib/test_ubsan.c: In function 'test_ubsan_out_of_bounds': ./lib/test_ubsan.c:115:22: warning: variable 'arr' set but not used [-Wunused-but-set-variable] 115 | volatile int arr[4]; | ^~~ ./lib/test_ubsan.c:114:23: warning: variable 'above' set but not used [-Wunused-but-set-variable] 114 | volatile char above[4] = { }; /* Protect surrounding memory. */ | ^~~~~ ./lib/test_ubsan.c: In function 'test_ubsan_load_invalid_value': ./lib/test_ubsan.c:137:44: warning: variable 'eptr' set but not used [-Wunused-but-set-variable] 137 | enum ubsan_test_enum eval, eval2, *eptr; | ^~~~ ./lib/test_ubsan.c:136:26: warning: variable 'ptr' set but not used [-Wunused-but-set-variable] 136 | bool val, val2, *ptr; | ^~~
-- Kees Cook
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