FTBFS if "-Werror=format-security" flag is used

[Mateusz Marzantowicz]

On 10.12.2013 00:01, Les Howell wrote:
> On Mon, 2013-12-09 at 15:59 -0700, Rich Megginson wrote:
>> On 12/09/2013 03:33 PM, Przemek Klosowski wrote:
>>
>>> On 12/06/2013 09:21 AM, Ralf Corsepius wrote:
>>>
>>>>
>>>> printf(string) is legitimate C, forcing "printf("%s", string) is
>>>> just silly. 
>>>>
>>> My apologies for being repetitive, but the original point is that
>>> printf(string) is insecure unless you can guarantee that you control
>>> 'string' now and forever. Also,  %s is the format for printing
>>> strings, so I just can't agree that coding printf("%s", string) is
>>> silly. 
>>
>> Silly is not the right word.  printf("%s", string) is inefficient.  In
>> this case, it would be better to use puts/fputs.
>>
> unless something has  changed recently fputs and puts just like gets and
> fgets have been deprecated and are discouraged due to potential security
> issues.
> 
> 

Something must have changed. GCC uses puts instead of printf in some
cases. Please, see below:

$ cat p.c
#include <stdio.h>

int main()
{
    printf("Hello world!\n");
    return 0;
}

$ gcc -S p.c

$ cat p.s
	.file	"p.c"
	.section	.rodata
.LC0:
	.string	"Hello world!"
	.text
	.globl	main
	.type	main, @function
main:
.LFB0:
	.cfi_startproc
	pushq	%rbp
	.cfi_def_cfa_offset 16
	.cfi_offset 6, -16
	movq	%rsp, %rbp
	.cfi_def_cfa_register 6
	movl	$.LC0, %edi
	call	puts
	movl	$0, %eax
	popq	%rbp
	.cfi_def_cfa 7, 8
	ret
	.cfi_endproc
.LFE0:
	.size	main, .-main
	.ident	"GCC: (GNU) 4.8.2 20131017 (Red Hat 4.8.2-1)"
	.section	.note.GNU-stack,"", at progbits


Mateusz Marzantowicz