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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>
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1 parent e7152b9 commit 096a8aac6bf4a5a0b2ef812ad76d056bbf3fb2af @kees kees committed with Jul 3, 2013
Showing with 10 additions and 13 deletions.
  1. +1 −2 drivers/acpi/sysfs.c
  2. +2 −4 drivers/s390/net/qeth_l3_sys.c
  3. +1 −2 drivers/staging/tidspbridge/rmgr/drv_interface.c
  4. +6 −5 fs/hppfs/hppfs.c
View
@@ -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;
@@ -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);
@@ -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);
View
@@ -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;
}

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