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author | Davi Arnaut <davi.arnaut@gmail.com> | 2006-03-24 03:18:42 -0800 |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-03-24 07:33:31 -0800 |
commit | 96840aa00a031069a136ec4c55d0bdd09ac6d3a7 (patch) | |
tree | f93592ca47f2412aa0cce3ce4c116d1678a42239 | |
parent | 6687a97d4041f996f725902d2990e5de6ef5cbe5 (diff) | |
download | linux-stable-96840aa00a031069a136ec4c55d0bdd09ac6d3a7.tar.gz linux-stable-96840aa00a031069a136ec4c55d0bdd09ac6d3a7.tar.bz2 linux-stable-96840aa00a031069a136ec4c55d0bdd09ac6d3a7.zip |
[PATCH] strndup_user()
This patch series creates a strndup_user() function to easy copying C strings
from userspace. Also we avoid common pitfalls like userspace modifying the
final \0 after the strlen_user().
Signed-off-by: Davi Arnaut <davi.arnaut@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r-- | include/linux/string.h | 2 | ||||
-rw-r--r-- | mm/util.c | 37 |
2 files changed, 39 insertions, 0 deletions
diff --git a/include/linux/string.h b/include/linux/string.h index 369be3264a55..dee221429ad0 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -18,6 +18,8 @@ extern char * strsep(char **,const char *); extern __kernel_size_t strspn(const char *,const char *); extern __kernel_size_t strcspn(const char *,const char *); +extern char *strndup_user(const char __user *, long); + /* * Include machine specific inline routines */ diff --git a/mm/util.c b/mm/util.c index 5f4bb59da63c..49e29f751b50 100644 --- a/mm/util.c +++ b/mm/util.c @@ -1,6 +1,8 @@ #include <linux/slab.h> #include <linux/string.h> #include <linux/module.h> +#include <linux/err.h> +#include <asm/uaccess.h> /** * kzalloc - allocate memory. The memory is set to zero. @@ -37,3 +39,38 @@ char *kstrdup(const char *s, gfp_t gfp) return buf; } EXPORT_SYMBOL(kstrdup); + +/* + * strndup_user - duplicate an existing string from user space + * + * @s: The string to duplicate + * @n: Maximum number of bytes to copy, including the trailing NUL. + */ +char *strndup_user(const char __user *s, long n) +{ + char *p; + long length; + + length = strnlen_user(s, n); + + if (!length) + return ERR_PTR(-EFAULT); + + if (length > n) + return ERR_PTR(-EINVAL); + + p = kmalloc(length, GFP_KERNEL); + + if (!p) + return ERR_PTR(-ENOMEM); + + if (copy_from_user(p, s, length)) { + kfree(p); + return ERR_PTR(-EFAULT); + } + + p[length - 1] = '\0'; + + return p; +} +EXPORT_SYMBOL(strndup_user); |