metag/ptrace: Preserve previous registers for short regset write

Dave Martin · gregkh · commit 2d9bc3695012 · 2017-03-31T09:49:54.000+02:00
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 &lt;Dave.Martin@arm.com&gt;
Acked-by: James Hogan &lt;james.hogan@imgtec.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
diff --git a/arch/metag/kernel/ptrace.c b/arch/metag/kernel/ptrace.c
@@ -303,7 +303,7 @@ static int metag_tls_set(struct task_struct *target,
 			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)

Original file line number	Diff line number	Diff line change
`@@ -303,7 +303,7 @@ static int metag_tls_set(struct task_struct *target,`
`303`	`303`	`const void kbuf, const void __user ubuf)`
`304`	`304`	`{`
`305`	`305`	`int ret;`
`306`		`- void __user *tls;`
	`306`	`+ void __user *tls = target->thread.tls_ptr;`
`307`	`307`
`308`	`308`	`ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &tls, 0, -1);`
`309`	`309`	`if (ret)`