| Message ID | 20250416-nolibc-ubsan-v1-2-c4704bb23da7@weissschuh.net (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | tools/nolibc: fix some undefined behaviour and enable UBSAN | expand |
On Wed, Apr 16, 2025 at 08:40:17PM +0200, Thomas Weißschuh wrote: > Both constructors and main() may be executed with different function > signatures than they are actually using. > This is intentional but trips up UBSAN. > > Disable the function sanitizer of UBSAN in _start_c(). > > Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> > --- > tools/include/nolibc/crt.h | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/tools/include/nolibc/crt.h b/tools/include/nolibc/crt.h > index c4b10103bbec50f1a3a0a4562e34fdbd1b43ce6f..961cfe777c3564e705dfdd581de828b374d05b0b 100644 > --- a/tools/include/nolibc/crt.h > +++ b/tools/include/nolibc/crt.h > @@ -7,6 +7,8 @@ > #ifndef _NOLIBC_CRT_H > #define _NOLIBC_CRT_H > > +#include "compiler.h" > + > char **environ __attribute__((weak)); > const unsigned long *_auxv __attribute__((weak)); > > @@ -25,6 +27,9 @@ extern void (*const __fini_array_end[])(void) __attribute__((weak)); > > void _start_c(long *sp); > __attribute__((weak,used)) > +#if __nolibc_has_feature(undefined_behavior_sanitizer) > + __attribute__((no_sanitize("function"))) > +#endif I'm wondering if it wouldn't be more reliable with: #if __nolibc_has_attribute(no_sanitize) __attribute__((no_sanitize("function"))) #endif Because in the end, what you want is to always place that attribute whenever it's supported, no ? > void _start_c(long *sp) > { > long argc; Willy
diff --git a/tools/include/nolibc/crt.h b/tools/include/nolibc/crt.h index c4b10103bbec50f1a3a0a4562e34fdbd1b43ce6f..961cfe777c3564e705dfdd581de828b374d05b0b 100644 --- a/tools/include/nolibc/crt.h +++ b/tools/include/nolibc/crt.h @@ -7,6 +7,8 @@ #ifndef _NOLIBC_CRT_H #define _NOLIBC_CRT_H +#include "compiler.h" + char **environ __attribute__((weak)); const unsigned long *_auxv __attribute__((weak)); @@ -25,6 +27,9 @@ extern void (*const __fini_array_end[])(void) __attribute__((weak)); void _start_c(long *sp); __attribute__((weak,used)) +#if __nolibc_has_feature(undefined_behavior_sanitizer) + __attribute__((no_sanitize("function"))) +#endif void _start_c(long *sp) { long argc;
Both constructors and main() may be executed with different function signatures than they are actually using. This is intentional but trips up UBSAN. Disable the function sanitizer of UBSAN in _start_c(). Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> --- tools/include/nolibc/crt.h | 5 +++++ 1 file changed, 5 insertions(+)