FAILED: patch "[PATCH] MIPS: Disallow outsized PTRACE_SETREGSET NT_PRFPREG regset" failed to apply to 3.18-stable tree

FAILED: patch "[PATCH] MIPS: Disallow outsized PTRACE_SETREGSET NT_PRFPREG regset" failed to apply to 3.18-stable tree

[gregkh]

The patch below does not apply to the 3.18-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From c8c5a3a24d395b14447a9a89d61586a913840a3b Mon Sep 17 00:00:00 2001
From: "Maciej W. Rozycki" <macro@mips.com>
Date: Mon, 11 Dec 2017 22:56:54 +0000
Subject: [PATCH] MIPS: Disallow outsized PTRACE_SETREGSET NT_PRFPREG regset
 accesses

Complement commit c23b3d1a5311 ("MIPS: ptrace: Change GP regset to use
correct core dump register layout") and also reject outsized
PTRACE_SETREGSET requests to the NT_PRFPREG regset, like with the
NT_PRSTATUS regset.

Signed-off-by: Maciej W. Rozycki <macro@mips.com>
Fixes: c23b3d1a5311 ("MIPS: ptrace: Change GP regset to use correct core dump register layout")
Cc: James Hogan <james.hogan@mips.com>
Cc: Paul Burton <Paul.Burton@mips.com>
Cc: Alex Smith <alex@alex-smith.me.uk>
Cc: Dave Martin <Dave.Martin@arm.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org # v3.17+
Patchwork: https://patchwork.linux-mips.org/patch/17930/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index 256908951a7c..0b23b1ad99e6 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -550,6 +550,9 @@ static int fpr_set(struct task_struct *target,
 
 	BUG_ON(count % sizeof(elf_fpreg_t));
 
+	if (pos + count > sizeof(elf_fpregset_t))
+		return -EIO;
+
 	init_fp_ctx(target);
 
 	if (sizeof(target->thread.fpu.fpr[0]) == sizeof(elf_fpreg_t))