sysctl: check length at deprecated_sysctl_warning

Original patch assumed args->nlen < CTL_MAXNAME, but it can be false.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 3a1744fed2b6..0deed82a6156 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2620,6 +2620,10 @@ static int deprecated_sysctl_warning(struct __sysctl_args *args)
         int name[CTL_MAXNAME];
         int i;
 
+        /* Check args->nlen. */
+        if (args->nlen < 0 || args->nlen > CTL_MAXNAME)
+                return -ENOTDIR;
+
         /* Read in the sysctl name for better debug message logging */
         for (i = 0; i < args->nlen; i++)
                 if (get_user(name[i], args->name + i))