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

Dave Martin · gregkh · commit fcc038db5959 · 2017-02-14T15:22:51.000-08:00
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: 5be6f62 ("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
@@ -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,

Original file line number	Diff line number	Diff line change
`@@ -600,7 +600,7 @@ static int gpr_set(struct task_struct *target,`
`600`	`600`	`const void kbuf, const void __user ubuf)`
`601`	`601`	`{`
`602`	`602`	`int ret;`
`603`		`- struct pt_regs newregs;`
	`603`	`+ struct pt_regs newregs = *task_pt_regs(target);`
`604`	`604`
`605`	`605`	`ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,`
`606`	`606`	`&newregs,`