Patch "Provide a function to create a NUL-terminated string from unterminated data" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    Provide a function to create a NUL-terminated string from unterminated data

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     provide-a-function-to-create-a-nul-terminated-string-from-unterminated-data.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From f35157417215ec138c920320c746fdb3e04ef1d5 Mon Sep 17 00:00:00 2001
From: David Howells <dhowells@redhat.com>
Date: Tue, 4 Jul 2017 17:25:02 +0100
Subject: Provide a function to create a NUL-terminated string from unterminated data

From: David Howells <dhowells@redhat.com>

commit f35157417215ec138c920320c746fdb3e04ef1d5 upstream.

Provide a function, kmemdup_nul(), that will create a NUL-terminated string
from an unterminated character array where the length is known in advance.

This is better than kstrndup() in situations where we already know the
string length as the strnlen() in kstrndup() is superfluous.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 include/linux/string.h |    1 +
 mm/util.c              |   24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+)

--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -123,6 +123,7 @@ extern char *kstrdup(const char *s, gfp_
 extern const char *kstrdup_const(const char *s, gfp_t gfp);
 extern char *kstrndup(const char *s, size_t len, gfp_t gfp);
 extern void *kmemdup(const void *src, size_t len, gfp_t gfp);
+extern char *kmemdup_nul(const char *s, size_t len, gfp_t gfp);
 
 extern char **argv_split(gfp_t gfp, const char *str, int *argcp);
 extern void argv_free(char **argv);
--- a/mm/util.c
+++ b/mm/util.c
@@ -80,6 +80,8 @@ EXPORT_SYMBOL(kstrdup_const);
  * @s: the string to duplicate
  * @max: read at most @max chars from @s
  * @gfp: the GFP mask used in the kmalloc() call when allocating memory
+ *
+ * Note: Use kmemdup_nul() instead if the size is known exactly.
  */
 char *kstrndup(const char *s, size_t max, gfp_t gfp)
 {
@@ -118,6 +120,28 @@ void *kmemdup(const void *src, size_t le
 EXPORT_SYMBOL(kmemdup);
 
 /**
+ * kmemdup_nul - Create a NUL-terminated string from unterminated data
+ * @s: The data to stringify
+ * @len: The size of the data
+ * @gfp: the GFP mask used in the kmalloc() call when allocating memory
+ */
+char *kmemdup_nul(const char *s, size_t len, gfp_t gfp)
+{
+	char *buf;
+
+	if (!s)
+		return NULL;
+
+	buf = kmalloc_track_caller(len + 1, gfp);
+	if (buf) {
+		memcpy(buf, s, len);
+		buf[len] = '\0';
+	}
+	return buf;
+}
+EXPORT_SYMBOL(kmemdup_nul);
+
+/**
  * memdup_user - duplicate memory region from user space
  *
  * @src: source address in user space


Patches currently in stable-queue which might be from dhowells@redhat.com are

queue-4.9/provide-a-function-to-create-a-nul-terminated-string-from-unterminated-data.patch