fix param_sysfs_builtin name length check

Commit faf8c714f4508207a9c81cc94dafc76ed6680b44 caused a regression:
parameter names longer than MAX_KBUILD_MODNAME will now be rejected,
although we just need to keep the module name part that short.  This patch
restores the old behaviour while still avoiding that memchr is called with
its length parameter larger than the total string length.

Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Cc: Dave Young <hidave.darkstar@gmail.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/params.c b/kernel/params.c
index 16f269e9ddc9b7d4ed129f98f0deac4965b87507..2a4c51487e7257e1865ae33d805a22e3dbb7f9ae 100644 (file)
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -592,19 +592,16 @@ static void __init param_sysfs_builtin(void)
 
        for (i=0; i < __stop___param - __start___param; i++) {
                char *dot;
-               size_t kplen;
+               size_t max_name_len;
 
                kp = &__start___param[i];
-               kplen = strlen(kp->name);
+               max_name_len =
+                       min_t(size_t, MAX_KBUILD_MODNAME, strlen(kp->name));
 
-               /* We do not handle args without periods. */
-               if (kplen > MAX_KBUILD_MODNAME) {
-                       DEBUGP("kernel parameter name is too long: %s\n", kp->name);
-                       continue;
-               }
-               dot = memchr(kp->name, '.', kplen);
+               dot = memchr(kp->name, '.', max_name_len);
                if (!dot) {
-                       DEBUGP("couldn't find period in %s\n", kp->name);
+                       DEBUGP("couldn't find period in first %d characters "
+                              "of %s\n", MAX_KBUILD_MODNAME, kp->name);
                        continue;
                }
                name_len = dot - kp->name;