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

Patch "arm64/ptrace: Preserve previous registers for short regset write" 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

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.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 9a17b876b573441bfb3387ad55d98bf7184daf9d Mon Sep 17 00:00:00 2001
From: Dave Martin <Dave.Martin@arm.com>
Date: Wed, 18 Jan 2017 16:25:20 +0000
Subject: arm64/ptrace: Preserve previous registers for short regset write

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

commit 9a17b876b573441bfb3387ad55d98bf7184daf9d upstream.

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

Fixes: 478fcb2cdb23 ("arm64: Debugging support")
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 |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -495,7 +495,7 @@ static int gpr_set(struct task_struct *t
 		   const void *kbuf, const void __user *ubuf)
 {
 	int ret;
-	struct user_pt_regs newregs;
+	struct user_pt_regs newregs = task_pt_regs(target)->user_regs;
 
 	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &newregs, 0, -1);
 	if (ret)
@@ -525,7 +525,8 @@ static int fpr_set(struct task_struct *t
 		   const void *kbuf, const void __user *ubuf)
 {
 	int ret;
-	struct user_fpsimd_state newstate;
+	struct user_fpsimd_state newstate =
+		target->thread.fpsimd_state.user_fpsimd;
 
 	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &newstate, 0, -1);
 	if (ret)
@@ -549,7 +550,7 @@ static int tls_set(struct task_struct *t
 		   const void *kbuf, const void __user *ubuf)
 {
 	int ret;
-	unsigned long tls;
+	unsigned long tls = target->thread.tp_value;
 
 	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &tls, 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