metag/ptrace: Reject partial NT_METAG_RPIPE writes

commit 7195ee3120d878259e8d94a5d9f808116f34d5ea upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/metag/kernel/ptrace.c b/arch/metag/kernel/ptrace.c
index 2e4dfc15abd330ac9a38cd2df6d1779cc6bd0d9b..5e2dc7defd2cea8f8895b028ab6adaa2c11f10d4 100644 (file)
--- 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);