From 75e2f882061487b65352d20cd844bdba507d55b7 Mon Sep 17 00:00:00 2001 From: gordon Date: Tue, 28 Jan 2020 18:53:14 +0000 Subject: [PATCH] Fix imprecise ordering of SSP canary initialization Submitted by: Kyle Evans Approved by: so Security: FreeBSD-EN-20:01.ssp --- lib/libc/secure/stack_protector.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/lib/libc/secure/stack_protector.c b/lib/libc/secure/stack_protector.c index 34bb7d0332a..63c02cd9603 100644 --- a/lib/libc/secure/stack_protector.c +++ b/lib/libc/secure/stack_protector.c @@ -40,11 +40,29 @@ __FBSDID("$FreeBSD$"); #include #include "libc_private.h" +/* + * We give __guard_setup a defined priority early on so that statically linked + * applications have a defined priority at which __stack_chk_guard will be + * getting initialized. This will not matter to most applications, because + * they're either not usually statically linked or they simply don't do things + * in constructors that would be adversely affected by their positioning with + * respect to this initialization. + * + * This conditional should be removed when GCC 4.2 is removed. + */ +#if __has_attribute(__constructor__) || __GNUC_PREREQ__(4, 3) +#define _GUARD_SETUP_CTOR_ATTR \ + __attribute__((__constructor__ (200), __used__)); +#else +#define _GUARD_SETUP_CTOR_ATTR \ + __attribute__((__constructor__, __used__)); +#endif + extern int __sysctl(const int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp, size_t newlen); long __stack_chk_guard[8] = {0, 0, 0, 0, 0, 0, 0, 0}; -static void __guard_setup(void) __attribute__((__constructor__, __used__)); +static void __guard_setup(void) _GUARD_SETUP_CTOR_ATTR; static void __fail(const char *); void __stack_chk_fail(void); void __chk_fail(void); -- 2.45.0