tile/ptrace: Preserve previous registers for short regset write

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

Cc: stable@vger.kernel.org
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Chris Metcalf <cmetcalf@mellanox.com>

diff --git a/arch/tile/kernel/ptrace.c b/arch/tile/kernel/ptrace.c
index d89b701..e279572 100644 (file)
--- a/arch/tile/kernel/ptrace.c
+++ b/arch/tile/kernel/ptrace.c
@@ -111,7 +111,7 @@ 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));