[patch added to 3.12-stable] tile/ptrace: Preserve previous registers for short regset write

[Jiri Slaby <jslaby@xxxxxxx>]

From: Dave Martin <Dave.Martin@xxxxxxx>

This patch has been added to the 3.12 stable tree. If you have any
objections, please let us know.

===============

commit fd7c99142d77dc4a851879a66715abf12a3193fb upstream.

Ensure that if userspace supplies insufficient data to
PTRACE_SETREGSET to fill all the registers, the thread's old
registers are preserved.

Signed-off-by: Dave Martin <Dave.Martin@xxxxxxx>
Signed-off-by: Chris Metcalf <cmetcalf@xxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 arch/tile/kernel/ptrace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/tile/kernel/ptrace.c b/arch/tile/kernel/ptrace.c
index de98c6ddf136..2343126c4ad2 100644
--- a/arch/tile/kernel/ptrace.c
+++ b/arch/tile/kernel/ptrace.c
@@ -110,7 +110,7 @@ static int tile_gpr_set(struct task_struct *target,
 			  const void *kbuf, const void __user *ubuf)
 {
 	int ret;
-	struct pt_regs regs;
+	struct pt_regs regs = *task_pt_regs(target);
 
 	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &regs, 0,
 				 sizeof(regs));
-- 
2.11.1