[tip:perf/core] perf/x86: Check user address explicitly in copy_from_user_nmi()

[tip-bot for Arun Sharma <asharma@fb.com>]

Commit-ID:  db0dc75d6403b6663c0eab4c6ccb672eb9b2ed72
Gitweb:     http://git.kernel.org/tip/db0dc75d6403b6663c0eab4c6ccb672eb9b2ed72
Author:     Arun Sharma <asharma@fb.com>
AuthorDate: Fri, 20 Apr 2012 15:41:36 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 6 Jun 2012 17:08:04 +0200

perf/x86: Check user address explicitly in copy_from_user_nmi()

Signed-off-by: Arun Sharma <asharma@fb.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1334961696-19580-5-git-send-email-asharma@fb.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/lib/usercopy.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c
index f61ee67..677b1ed 100644
--- a/arch/x86/lib/usercopy.c
+++ b/arch/x86/lib/usercopy.c
@@ -8,6 +8,7 @@
 #include <linux/module.h>
 
 #include <asm/word-at-a-time.h>
+#include <linux/sched.h>
 
 /*
  * best effort, GUP based copy_from_user() that is NMI-safe
@@ -21,6 +22,9 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
 	void *map;
 	int ret;
 
+	if (__range_not_ok(from, n, TASK_SIZE) == 0)
+		return len;
+
 	do {
 		ret = __get_user_pages_fast(addr, 1, 0, &page);
 		if (!ret)