metag/ptrace: Reject partial NT_METAG_RPIPE writes

It's not clear what behaviour is sensible when doing partial write of
NT_METAG_RPIPE, so just don't bother.

This patch assumes that userspace will never rely on a partial SETREGSET
in this case, since it's not clear what should happen anyway.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/metag/kernel/ptrace.c b/arch/metag/kernel/ptrace.c
index 2e4dfc15abd3..5e2dc7defd2c 100644
--- a/arch/metag/kernel/ptrace.c
+++ b/arch/metag/kernel/ptrace.c
@@ -253,6 +253,8 @@ int metag_rp_state_copyin(struct pt_regs *regs,
         unsigned long long *ptr;
         int ret, i;
 
+        if (count < 4*13)
+                return -EINVAL;
         /* Read the entire pipeline before making any changes */
         ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
                                  &rp, 0, 4*13);