[Bug middle-end/25957] New: -fstack-protector code on i386/x86-64 can be improved.

[ak at muc dot de]

Compiling this simple test case with

GNU C version 4.2.0 20060118 (experimental) (x86_64-unknown-linux-gnu)

extern void f2(char *s);
void f(void) 
{
        char x[100];
        f2(x);
}

i get

...
        xorq    __stack_chk_guard(%rip), %rax
        jne     .L5
        addq    $120, %rsp
        ret
.L5:
        .p2align 4,,5
        call    __stack_chk_fail

Suggestions for improvement:
- It shouldn't use p2align 4,,5 for the __stack_chk_fail trampoline
because that wastes space in very infrequent code
- It should use jne to jump the function directly because it 
should never return (when it is called the stack is compromised
and it would be a security hole)


-- 
           Summary: -fstack-protector code on i386/x86-64 can be improved.
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: ak at muc dot de
  GCC host triplet: x86_64-linux
GCC target triplet: x86_64-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25957