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 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
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-4.4 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 @@ -122,6 +122,7 @@ 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-4.4/provide-a-function-to-create-a-nul-terminated-string-from-unterminated-data.patch