[PATCH next] nxen/xenbus: Replace strcpy() with memcpy()

[david.laight.linux@gmail.com]

From: David Laight <david.laight.linux@gmail.com>

The length of the string is calculated in order to allocate the correct
sized memory block, use the same length to copy the string.

Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
This is one of a group of patches that remove potentially unbounded
strcpy() calls.

They are mostly replaced by strscpy() or, when strlen() has just been
called, with memcpy() (usually including the '\0').

Calls with copy string literals into arrays are left unchanged.
They are safe and easily detected as such.

The changes were made by getting the compiler to detect the calls and
then fixing the code by hand.

Note that all the changes are only compile tested.

Some Makefiles were changed to allow files to contain strcpy().
As well as 'difficult to fix' files, this included 'show' functions
as they really need to use sysfs_emit() or seq_printf().

All the patches are being sent individually to avoid very long cc lists.
Apologies for the terse commit messages and likely unexpected tags.
(There are about 100 patches in total.)

 drivers/xen/xenbus/xenbus_probe.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index eb260eceb4d2..fafb2b84fa5c 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -514,7 +514,7 @@ int xenbus_probe_node(struct xen_bus_type *bus,
 	char devname[XEN_BUS_ID_SIZE];
 	int err;
 	struct xenbus_device *xendev;
-	size_t stringlen;
+	size_t name_len, type_len;
 	char *tmpstring;
 
 	enum xenbus_state state = xenbus_read_driver_state(NULL, nodename);
@@ -525,8 +525,9 @@ int xenbus_probe_node(struct xen_bus_type *bus,
 		return 0;
 	}
 
-	stringlen = strlen(nodename) + 1 + strlen(type) + 1;
-	xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
+	name_len = strlen(nodename);
+	type_len = strlen(type);
+	xendev = kzalloc(sizeof(*xendev) + name_len + 1 + type_len + 1, GFP_KERNEL);
 	if (!xendev)
 		return -ENOMEM;
 
@@ -535,11 +536,11 @@ int xenbus_probe_node(struct xen_bus_type *bus,
 	/* Copy the strings into the extra space. */
 
 	tmpstring = (char *)(xendev + 1);
-	strcpy(tmpstring, nodename);
+	memcpy(tmpstring, nodename, name_len);
 	xendev->nodename = tmpstring;
 
-	tmpstring += strlen(tmpstring) + 1;
-	strcpy(tmpstring, type);
+	tmpstring += name_len + 1;
+	memcpy(tmpstring, type, type_len);
 	xendev->devicetype = tmpstring;
 	init_completion(&xendev->down);
 
-- 
2.39.5