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authorIngo Molnar <mingo@elte.hu>2008-02-26 12:55:57 +0100
committerIngo Molnar <mingo@elte.hu>2008-02-26 12:55:57 +0100
commit5d119b2c9a490e2d647eae134211b32a18a04c7d (patch)
tree37f40ec2e3ae4ad793d6c4c40f253e4266895d09
parentce28b9864b853803320c3f1d8de1b81aa4120b14 (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.S6
-rw-r--r--arch/x86/kernel/process_64.c6
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, &regs);
+ error = do_execve(filename, argv, envp, regs);
putname(filename);
return error;
}