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>

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 3a1744fed2b68d589da4cbf4e5f088e652066262..0deed82a61568d6660a7f4ee625c490ffecffcc5 100644 (file)
--- 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))