The patch titled
kmemdup: introduce
has been removed from the -mm tree. Its filename is
kmemdup-introduce.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: kmemdup: introduce
From: Alexey Dobriyan <adobriyan@xxxxxxxxx>
One of idiomatic ways to duplicate a region of memory is
dst = kmalloc(len, GFP_KERNEL);
if (!dst)
return -ENOMEM;
memcpy(dst, src, len);
which is neat code except a programmer needs to write size twice. Which
sometimes leads to mistakes. If len passed to kmalloc is smaller that len
passed to memcpy, it's straight overwrite-beyond-end. If len passed to
memcpy is smaller than len passed to kmalloc, it's either a) legit
behaviour ;-), or b) cloned buffer will contain garbage in second half.
Slight trolling of commit lists shows several duplications bugs
done exactly because of diverged lenghts:
Linux:
[CRYPTO]: Fix memcpy/memset args.
[PATCH] memcpy/memset fixes
OpenBSD:
kerberosV/src/lib/asn1: der_copy.c:1.4
If programmer is given only one place to play with lengths, I believe, such
mistakes could be avoided.
With kmemdup, the snippet above will be rewritten as:
dst = kmemdup(src, len, GFP_KERNEL);
if (!dst)
return -ENOMEM;
This also leads to smaller code (kzalloc effect). Quick grep shows
200+ places where kmemdup() can be used.
Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
include/linux/string.h | 1 +
mm/util.c | 18 ++++++++++++++++++
2 files changed, 19 insertions(+)
diff -puN include/linux/string.h~kmemdup-introduce include/linux/string.h
--- a/include/linux/string.h~kmemdup-introduce
+++ a/include/linux/string.h
@@ -99,6 +99,7 @@ extern void * memchr(const void *,int,__
#endif
extern char *kstrdup(const char *s, gfp_t gfp);
+extern void *kmemdup(const void *src, size_t len, gfp_t gfp);
#ifdef __cplusplus
}
diff -puN mm/util.c~kmemdup-introduce mm/util.c
--- a/mm/util.c~kmemdup-introduce
+++ a/mm/util.c
@@ -40,6 +40,24 @@ char *kstrdup(const char *s, gfp_t gfp)
}
EXPORT_SYMBOL(kstrdup);
+/**
+ * kmemdup - duplicate region of memory
+ *
+ * @src: memory region to duplicate
+ * @len: memory region length
+ * @gfp: GFP mask to use
+ */
+void *kmemdup(const void *src, size_t len, gfp_t gfp)
+{
+ void *p;
+
+ p = ____kmalloc(len, gfp);
+ if (p)
+ memcpy(p, src, len);
+ return p;
+}
+EXPORT_SYMBOL(kmemdup);
+
/*
* strndup_user - duplicate an existing string from user space
*
_
Patches currently in -mm which might be from adobriyan@xxxxxxxxx are
origin.patch
asus_acpi-fix-proc-files-parsing.patch
asus_acpi-dont-printk-on-writing-garbage-to-proc-files.patch
config_pm=n-slim-drivers-pcmcia.patch
i82092-wire-up-errors-from-pci_register_driver.patch
git-serial.patch
git-scsi-misc.patch
megaraid-fix-warnings-when-config_proc_fs=n.patch
kmemdup-introduce-vs-slab-clean-up-leak-tracking-ifdefs-a-little-bit.patch
remove-null-check-in-register_nls.patch
make-kmem_cache_destroy-return-void-ecryptfs.patch
config_pm=n-slim-drivers-ide-pci-sc1200c.patch
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