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>

4 files changed, 10 insertions, 13 deletions

diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c
index fcae5fa2e1b3..193745d96fcc 100644
--- a/drivers/acpi/sysfs.c
+++ b/drivers/acpi/sysfs.c
@@ -677,10 +677,9 @@ void acpi_irq_stats_init(void)
 		else
 			sprintf(buffer, "bug%02X", i);
 
-		name = kzalloc(strlen(buffer) + 1, GFP_KERNEL);
+		name = kstrdup(buffer, GFP_KERNEL);
 		if (name == NULL)
 			goto fail;
-		strncpy(name, buffer, strlen(buffer) + 1);
 
 		sysfs_attr_init(&counter_attrs[i].attr);
 		counter_attrs[i].attr.name = name;
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);
diff --git a/drivers/staging/tidspbridge/rmgr/drv_interface.c b/drivers/staging/tidspbridge/rmgr/drv_interface.c
index 9c020562c846..6d04eb48bfbc 100644
--- a/drivers/staging/tidspbridge/rmgr/drv_interface.c
+++ b/drivers/staging/tidspbridge/rmgr/drv_interface.c
@@ -421,12 +421,11 @@ static int omap3_bridge_startup(struct platform_device *pdev)
 	drv_datap->tc_wordswapon = tc_wordswapon;
 
 	if (base_img) {
-		drv_datap->base_img = kmalloc(strlen(base_img) + 1, GFP_KERNEL);
+		drv_datap->base_img = kstrdup(base_img, GFP_KERNEL);
 		if (!drv_datap->base_img) {
 			err = -ENOMEM;
 			goto err2;
 		}
-		strncpy(drv_datap->base_img, base_img, strlen(base_img) + 1);
 	}
 
 	dev_set_drvdata(bridge, drv_datap);
diff --git a/fs/hppfs/hppfs.c b/fs/hppfs/hppfs.c
index fc90ab11c340..4338ff32959d 100644
--- a/fs/hppfs/hppfs.c
+++ b/fs/hppfs/hppfs.c
@@ -69,7 +69,7 @@ static char *dentry_name(struct dentry *dentry, int extra)
 	struct dentry *parent;
 	char *root, *name;
 	const char *seg_name;
-	int len, seg_len;
+	int len, seg_len, root_len;
 
 	len = 0;
 	parent = dentry;
@@ -81,7 +81,8 @@ static char *dentry_name(struct dentry *dentry, int extra)
 	}
 
 	root = "proc";
-	len += strlen(root);
+	root_len = strlen(root);
+	len += root_len;
 	name = kmalloc(len + extra + 1, GFP_KERNEL);
 	if (name == NULL)
 		return NULL;
@@ -91,7 +92,7 @@ static char *dentry_name(struct dentry *dentry, int extra)
 	while (parent->d_parent != parent) {
 		if (is_pid(parent)) {
 			seg_name = "pid";
-			seg_len = strlen("pid");
+			seg_len = strlen(seg_name);
 		}
 		else {
 			seg_name = parent->d_name.name;
@@ -100,10 +101,10 @@ static char *dentry_name(struct dentry *dentry, int extra)
 
 		len -= seg_len + 1;
 		name[len] = '/';
-		strncpy(&name[len + 1], seg_name, seg_len);
+		memcpy(&name[len + 1], seg_name, seg_len);
 		parent = parent->d_parent;
 	}
-	strncpy(name, root, strlen(root));
+	memcpy(name, root, root_len);
 	return name;
 }