ARM: 8643/3: arm/ptrace: Preserve previous registers for short regset write

commit 228dbbfb5d77f8e047b2a1d78da14b7158433027 upstream.

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

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 4d9375814b538e096b57f76d947916cb3ce92b7a..d54c53b7ab6355388b2f179ab8439475bf3b86a6 100644 (file)
--- 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,