The patch titled
Subject: mm/util: deduplicate code in {kstrdup,kstrndup,kmemdup_nul}
has been added to the -mm mm-nonmm-unstable branch. Its filename is
mm-util-deduplicate-code-in-kstrdupkstrndupkmemdup_nul.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-util-deduplicate-code-in-kstrdupkstrndupkmemdup_nul.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Yafang Shao <laoar.shao@xxxxxxxxx>
Subject: mm/util: deduplicate code in {kstrdup,kstrndup,kmemdup_nul}
Date: Mon, 7 Oct 2024 22:49:10 +0800
These three functions follow the same pattern. To deduplicate the code,
let's introduce a common helper __kmemdup_nul().
Link: https://lkml.kernel.org/r/20241007144911.27693-7-laoar.shao@xxxxxxxxx
Suggested-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
Cc: Simon Horman <horms@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Alejandro Colomar <alx@xxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx>
Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxxx>
Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Eric Paris <eparis@xxxxxxxxxx>
Cc: James Morris <jmorris@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Justin Stitt <justinstitt@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Matus Jokay <matus.jokay@xxxxxxxx>
Cc: Maxime Ripard <mripard@xxxxxxxxxx>
Cc: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
Cc: Paul Moore <paul@xxxxxxxxxxxxxx>
Cc: Quentin Monnet <qmo@xxxxxxxxxx>
Cc: "Serge E. Hallyn" <serge@xxxxxxxxxx>
Cc: Stephen Smalley <stephen.smalley.work@xxxxxxxxx>
Cc: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/util.c | 69 ++++++++++++++++++++--------------------------------
1 file changed, 27 insertions(+), 42 deletions(-)
--- a/mm/util.c~mm-util-deduplicate-code-in-kstrdupkstrndupkmemdup_nul
+++ a/mm/util.c
@@ -45,34 +45,41 @@ void kfree_const(const void *x)
EXPORT_SYMBOL(kfree_const);
/**
- * kstrdup - allocate space for and copy an existing string
- * @s: the string to duplicate
+ * __kmemdup_nul - Create a NUL-terminated string from @s, which might be unterminated.
+ * @s: The data to copy
+ * @len: The size of the data, not including the NUL terminator
* @gfp: the GFP mask used in the kmalloc() call when allocating memory
*
- * Return: newly allocated copy of @s or %NULL in case of error
+ * Return: newly allocated copy of @s with NUL-termination or %NULL in
+ * case of error
*/
-noinline
-char *kstrdup(const char *s, gfp_t gfp)
+static __always_inline char *__kmemdup_nul(const char *s, size_t len, gfp_t gfp)
{
- size_t len;
char *buf;
- if (!s)
+ /* '+1' for the NUL terminator */
+ buf = kmalloc_track_caller(len + 1, gfp);
+ if (!buf)
return NULL;
- len = strlen(s) + 1;
- buf = kmalloc_track_caller(len, gfp);
- if (buf) {
- memcpy(buf, s, len);
- /*
- * During memcpy(), the string might be updated to a new value,
- * which could be longer than the string when strlen() is
- * called. Therefore, we need to add a NUL terminator.
- */
- buf[len - 1] = '\0';
- }
+ memcpy(buf, s, len);
+ /* Ensure the buf is always NUL-terminated, regardless of @s. */
+ buf[len] = '\0';
return buf;
}
+
+/**
+ * kstrdup - allocate space for and copy an existing string
+ * @s: the string to duplicate
+ * @gfp: the GFP mask used in the kmalloc() call when allocating memory
+ *
+ * Return: newly allocated copy of @s or %NULL in case of error
+ */
+noinline
+char *kstrdup(const char *s, gfp_t gfp)
+{
+ return s ? __kmemdup_nul(s, strlen(s), gfp) : NULL;
+}
EXPORT_SYMBOL(kstrdup);
/**
@@ -107,19 +114,7 @@ EXPORT_SYMBOL(kstrdup_const);
*/
char *kstrndup(const char *s, size_t max, gfp_t gfp)
{
- size_t len;
- char *buf;
-
- if (!s)
- return NULL;
-
- len = strnlen(s, max);
- buf = kmalloc_track_caller(len+1, gfp);
- if (buf) {
- memcpy(buf, s, len);
- buf[len] = '\0';
- }
- return buf;
+ return s ? __kmemdup_nul(s, strnlen(s, max), gfp) : NULL;
}
EXPORT_SYMBOL(kstrndup);
@@ -193,17 +188,7 @@ EXPORT_SYMBOL(kvmemdup);
*/
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;
+ return s ? __kmemdup_nul(s, len, gfp) : NULL;
}
EXPORT_SYMBOL(kmemdup_nul);
_
Patches currently in -mm which might be from laoar.shao@xxxxxxxxx are
get-rid-of-__get_task_comm.patch
auditsc-replace-memcpy-with-strscpy.patch
security-replace-memcpy-with-get_task_comm.patch
bpftool-ensure-task-comm-is-always-nul-terminated.patch
mm-util-fix-possible-race-condition-in-kstrdup.patch
mm-util-deduplicate-code-in-kstrdupkstrndupkmemdup_nul.patch
drm-replace-strcpy-with-strscpy.patch
