[PATCH] sysctl: don't read uninit memory in deprecated_sysctl_warning()

From	Alexander Potapenko <glider@google.com>
Newsgroups	linux.kernel
Subject	[PATCH] sysctl: don't read uninit memory in deprecated_sysctl_warning()
Date	2017-06-28 17:10 +0200
Message-ID	<tXmLo-8q5-39@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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Don't attempt to read the first two elements of name[] unless they
were actually copied from the userspace.

This bug has been detected by KMSAN.

Signed-off-by: Alexander Potapenko <glider@google.com>
---
 kernel/sysctl_binary.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c
index ece4b177052b..38d6ba22a209 100644
--- a/kernel/sysctl_binary.c
+++ b/kernel/sysctl_binary.c
@@ -1346,7 +1346,7 @@ static void deprecated_sysctl_warning(const int *name, int nlen)
 	 * CTL_KERN/KERN_VERSION is used by older glibc and cannot
 	 * ever go away.
 	 */
-	if (name[0] == CTL_KERN && name[1] == KERN_VERSION)
+	if (nlen >= 2 && name[0] == CTL_KERN && name[1] == KERN_VERSION)
 		return;
 
 	if (printk_ratelimit()) {
-- 
2.13.2.725.g09c95d1e9-goog

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[PATCH] sysctl: don't read uninit memory in deprecated_sysctl_warning() Alexander Potapenko <glider@google.com> - 2017-06-28 17:10 +0200
  Re: [PATCH] sysctl: don't read uninit memory in  deprecated_sysctl_warning() Andrew Morton <akpm@linux-foundation.org> - 2017-06-30 00:40 +0200

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