[PATCH 3.18 025/124] metag/ptrace: Preserve previous registers for short regset write

From: Greg Kroah-Hartman
Date: Thu Apr 20 2017 - 02:38:05 EST


3.18-stable review patch. If anyone has any objections, please let me know.

------------------

From: Dave Martin <Dave.Martin@xxxxxxx>

commit a78ce80d2c9178351b34d78fec805140c29c193e 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>
Acked-by: James Hogan <james.hogan@xxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
arch/metag/kernel/ptrace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/metag/kernel/ptrace.c
+++ b/arch/metag/kernel/ptrace.c
@@ -303,7 +303,7 @@ static int metag_tls_set(struct task_str
const void *kbuf, const void __user *ubuf)
{
int ret;
- void __user *tls;
+ void __user *tls = target->thread.tls_ptr;

ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &tls, 0, -1);
if (ret)