[PATCH 3.16 110/254] MIPS: Disallow outsized PTRACE_SETREGSET NT_PRFPREG regset accesses

[Ben Hutchings]

3.16.55-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: "Maciej W. Rozycki" <macro@xxxxxxxx>

commit c8c5a3a24d395b14447a9a89d61586a913840a3b upstream.

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@xxxxxxxx>
Fixes: c23b3d1a5311 ("MIPS: ptrace: Change GP regset to use correct core dump register layout")
Cc: James Hogan <james.hogan@xxxxxxxx>
Cc: Paul Burton <Paul.Burton@xxxxxxxx>
Cc: Alex Smith <alex@xxxxxxxxxxxxxxxx>
Cc: Dave Martin <Dave.Martin@xxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Patchwork: https://patchwork.linux-mips.org/patch/17930/
Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 arch/mips/kernel/ptrace.c | 3 +++
 1 file changed, 3 insertions(+)

--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -568,6 +568,9 @@ static int fpr_set(struct task_struct *t
 
 	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))