Messages in this thread Patch in this message | | | Date | Wed, 2 Feb 2022 08:01:49 -0800 | From | Guenter Roeck <> | Subject | Re: [PATCH] lib/test_string.c: Add test for strlen() |
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On Sun, Jan 30, 2022 at 10:36:53AM -0800, Kees Cook wrote: > Add a simple test for strlen() functionality, including using it as a > constant expression. > > Cc: Geert Uytterhoeven <geert@linux-m68k.org> > Cc: Peter Rosin <peda@axentia.se> > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > I'll be taking this as part of my Clang FORTIFY_SOURCE series. > --- > lib/test_string.c | 37 +++++++++++++++++++++++++++++++++++++ > 1 file changed, 37 insertions(+) > > diff --git a/lib/test_string.c b/lib/test_string.c > index 9dfd6f52de92..59994f552c48 100644 > --- a/lib/test_string.c > +++ b/lib/test_string.c > @@ -179,6 +179,38 @@ static __init int strnchr_selftest(void) > return 0; > } > > +/* > + * Unlike many other string functions, strlen() can be used in > + * static initializers when string lengths are known at compile > + * time. (i.e. Under these conditions, strlen() is a constant > + * expression.) Make sure it can be used this way. > + */ > +static const int strlen_ce = strlen("tada, a constant expression"); > +
This results in:
lib/test_string.c:188:30: error: initializer element is not constant 188 | static const int strlen_ce = strlen("tada, a constant expression");
for several of my tests. I don't think you can mandate that a compiler implements this.
Guenter
> +static __init int strlen_selftest(void) > +{ > + /* String length ruler: 123456789012345 */ > + static const char normal[] = "I am normal"; > + static const char *ptr = "where do I go?"; > + static const char trailing[] = "hidden NULLs\0\0\0"; > + static const char leading[] = "\0\0hidden text"; > + > + if (strlen(normal) != 11) > + return 0x100001; > + if (strlen(ptr++) != 14) > + return 0x100002; > + if (strlen(ptr++) != 13) > + return 0x100003; > + if (strlen(trailing) != 12) > + return 0x100004; > + if (strlen(leading) != 0) > + return 0x100005; > + if (strlen_ce != 27) > + return 0x100006; > + > + return 0; > +} > + > static __exit void string_selftest_remove(void) > { > } > @@ -212,6 +244,11 @@ static __init int string_selftest_init(void) > if (subtest) > goto fail; > > + test = 5; > + subtest = strlen_selftest(); > + if (subtest) > + goto fail; > + > pr_info("String selftests succeeded\n"); > return 0; > fail: > -- > 2.30.2 >
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