x86: fix execve with -fstack-protect

pointed out by pageexec@freemail.hu:

> what happens here is that gcc treats the argument area as owned by the
> callee, not the caller and is allowed to do certain tricks. for ssp it
> will make a copy of the struct passed by value into the local variable
> area and pass *its* address down, and it won't copy it back into the
> original instance stored in the argument area.
>
> so once sys_execve returns, the pt_regs passed by value hasn't at all
> changed and its default content will cause a nice double fault (FWIW,
> this part took me the longest to debug, being down with cold didn't
> help it either ;).

To fix this we pass in pt_regs by pointer.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 3 insertions, 3 deletions

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index b0cc8f0136d8..43f287744f9f 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -730,16 +730,16 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
  */
 asmlinkage
 long sys_execve(char __user *name, char __user * __user *argv,
-		char __user * __user *envp, struct pt_regs regs)
+		char __user * __user *envp, struct pt_regs *regs)
 {
 	long error;
 	char * filename;
 
 	filename = getname(name);
 	error = PTR_ERR(filename);
-	if (IS_ERR(filename)) 
+	if (IS_ERR(filename))
 		return error;
-	error = do_execve(filename, argv, envp, &regs); 
+	error = do_execve(filename, argv, envp, regs);
 	putname(filename);
 	return error;
 }