Patch "arm64/ptrace: Preserve previous registers for short regset write - 2" has been added to the 4.4-stable tree

Patch "arm64/ptrace: Preserve previous registers for short regset write - 2" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    arm64/ptrace: Preserve previous registers for short regset write - 2

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     arm64-ptrace-preserve-previous-registers-for-short-regset-write-2.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 9dd73f72f218320c6c90da5f834996e7360dc227 Mon Sep 17 00:00:00 2001
From: Dave Martin <Dave.Martin@arm.com>
Date: Wed, 18 Jan 2017 16:25:21 +0000
Subject: arm64/ptrace: Preserve previous registers for short regset write - 2

From: Dave Martin <Dave.Martin@arm.com>

commit 9dd73f72f218320c6c90da5f834996e7360dc227 upstream.

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

Fixes: 766a85d7bc5d ("arm64: ptrace: add NT_ARM_SYSTEM_CALL regset")
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Will Deacon <Will.Deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm64/kernel/ptrace.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -576,7 +576,8 @@ static int system_call_set(struct task_s
 			   unsigned int pos, unsigned int count,
 			   const void *kbuf, const void __user *ubuf)
 {
-	int syscallno, ret;
+	int syscallno = task_pt_regs(target)->syscallno;
+	int ret;
 
 	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &syscallno, 0, -1);
 	if (ret)


Patches currently in stable-queue which might be from Dave.Martin@arm.com are

queue-4.4/arm64-ptrace-preserve-previous-registers-for-short-regset-write-3.patch
queue-4.4/arm64-ptrace-reject-attempts-to-set-incomplete-hardware-breakpoint-fields.patch
queue-4.4/arm64-ptrace-preserve-previous-registers-for-short-regset-write-2.patch
queue-4.4/arm64-ptrace-avoid-uninitialised-struct-padding-in-fpr_set.patch
queue-4.4/arm64-ptrace-preserve-previous-registers-for-short-regset-write.patch