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

[Alexander Potapenko]

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 <gli...@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