clean up scary strncpy(dst, src, strlen(src)) uses

Fix various weird constructions of strncpy(dst, src, strlen(src)).

Length limits should be about the space available in the destination,
not repurposed as a method to either always include or always exclude a
trailing NULL byte.  Either the NULL should always be copied (using
strlcpy), or it should not be copied (using something like memcpy).
Readable code should not depend on the weird behavior of strncpy when it
hits the length limit.  Better to avoid the anti-pattern entirely.

[akpm@linux-foundation.org: revert getdelays.c part due to missing bsd/string.h]
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>	[staging]
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>	[acpi]
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ursula Braun <ursula.braun@de.ibm.com>
Cc: Frank Blaschka <blaschka@linux.vnet.ibm.com>
Cc: Richard Weinberger <richard@nod.at>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 4 deletions

diff --git a/drivers/s390/net/qeth_l3_sys.c b/drivers/s390/net/qeth_l3_sys.c
index e70af2406ff9..d1c8025b0b03 100644
--- a/drivers/s390/net/qeth_l3_sys.c
+++ b/drivers/s390/net/qeth_l3_sys.c
@@ -315,10 +315,8 @@ static ssize_t qeth_l3_dev_hsuid_store(struct device *dev,
         if (qeth_configure_cq(card, QETH_CQ_ENABLED))
                 return -EPERM;
 
-        for (i = 0; i < 8; i++)
-                card->options.hsuid[i] = ' ';
-        card->options.hsuid[8] = '\0';
-        strncpy(card->options.hsuid, tmp, strlen(tmp));
+        snprintf(card->options.hsuid, sizeof(card->options.hsuid),
+                 "%-8s", tmp);
         ASCEBC(card->options.hsuid, 8);
         if (card->dev)
                 memcpy(card->dev->perm_addr, card->options.hsuid, 9);