[PATCH 3.12 108/142] metag/ptrace: Reject partial NT_METAG_RPIPE writes

[Jiri Slaby]

From: Dave Martin <Dave.Martin@xxxxxxx>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

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@xxxxxxx>
Acked-by: James Hogan <james.hogan@xxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 arch/metag/kernel/ptrace.c | 2 ++
 1 file changed, 2 insertions(+)

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);
-- 
2.12.2