diff options
| author | Ingo Molnar <mingo@elte.hu> | 2008-02-26 12:55:57 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-02-26 12:55:57 +0100 |
| commit | 5d119b2c9a490e2d647eae134211b32a18a04c7d (patch) | |
| tree | 37f40ec2e3ae4ad793d6c4c40f253e4266895d09 | |
| parent | ce28b9864b853803320c3f1d8de1b81aa4120b14 (diff) | |
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>
| -rw-r--r-- | arch/x86/kernel/entry_64.S | 6 | ||||
| -rw-r--r-- | arch/x86/kernel/process_64.c | 6 |
2 files changed, 7 insertions, 5 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 2ad9a1bc6a7..c20c9e7e08d 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -453,6 +453,7 @@ ENTRY(stub_execve) CFI_REGISTER rip, r11 SAVE_REST FIXUP_TOP_OF_STACK %r11 + movq %rsp, %rcx call sys_execve RESTORE_TOP_OF_STACK %r11 movq %rax,RAX(%rsp) @@ -1036,15 +1037,16 @@ ENDPROC(child_rip) * rdi: name, rsi: argv, rdx: envp * * We want to fallback into: - * extern long sys_execve(char *name, char **argv,char **envp, struct pt_regs regs) + * extern long sys_execve(char *name, char **argv,char **envp, struct pt_regs *regs) * * do_sys_execve asm fallback arguments: - * rdi: name, rsi: argv, rdx: envp, fake frame on the stack + * rdi: name, rsi: argv, rdx: envp, rcx: fake frame on the stack */ ENTRY(kernel_execve) CFI_STARTPROC FAKE_STACK_FRAME $0 SAVE_ALL + movq %rsp,%rcx call sys_execve movq %rax, RAX(%rsp) RESTORE_REST diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index b0cc8f0136d..43f287744f9 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, ®s); + error = do_execve(filename, argv, envp, regs); putname(filename); return error; } |