From: Dave Martin <Dave.Martin@arm.com>
Date: Wed, 18 Jan 2017 16:11:56 +0000 (+0100)
Subject: ARM: 8643/3: arm/ptrace: Preserve previous registers for short regset write
X-Git-Tag: v4.10-rc8~20^2
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=228dbbfb5d77f8e047b2a1d78da14b7158433027;p=linux.git

ARM: 8643/3: arm/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> # 3.0.x-
Fixes: 5be6f62b0059 ("ARM: 6883/1: ptrace: Migrate to regsets framework")
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---

diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index ce131ed5939d..ae738a6319f6 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -600,7 +600,7 @@ static int gpr_set(struct task_struct *target,
 		   const void *kbuf, const void __user *ubuf)
 {
 	int ret;
-	struct pt_regs newregs;
+	struct pt_regs newregs = *task_pt_regs(target);
 
 	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 				 &newregs,