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author | Al Viro <viro@zeniv.linux.org.uk> | 2015-12-24 00:06:05 -0500 |
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committer | Al Viro <viro@zeniv.linux.org.uk> | 2016-01-04 10:20:19 -0500 |
commit | e9d408e107db9a554b36c3a79f67b37dd3e16da0 (patch) | |
tree | 97383e40e388aa302828ffb2ddd845b257109118 | |
parent | 74bf8efb5fa6e958d2d7c7917b8bb672085ec0c6 (diff) | |
download | op-kernel-dev-e9d408e107db9a554b36c3a79f67b37dd3e16da0.zip op-kernel-dev-e9d408e107db9a554b36c3a79f67b37dd3e16da0.tar.gz |
new helper: memdup_user_nul()
Similar to memdup_user(), except that allocated buffer is one byte
longer and '\0' is stored after the copied data.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r-- | include/linux/string.h | 1 | ||||
-rw-r--r-- | mm/util.c | 31 |
2 files changed, 32 insertions, 0 deletions
diff --git a/include/linux/string.h b/include/linux/string.h index 9ef7795..9eebc66 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -10,6 +10,7 @@ extern char *strndup_user(const char __user *, long); extern void *memdup_user(const void __user *, size_t); +extern void *memdup_user_nul(const void __user *, size_t); /* * Include machine specific inline routines @@ -176,6 +176,37 @@ char *strndup_user(const char __user *s, long n) } EXPORT_SYMBOL(strndup_user); +/** + * memdup_user_nul - duplicate memory region from user space and NUL-terminate + * + * @src: source address in user space + * @len: number of bytes to copy + * + * Returns an ERR_PTR() on failure. + */ +void *memdup_user_nul(const void __user *src, size_t len) +{ + char *p; + + /* + * Always use GFP_KERNEL, since copy_from_user() can sleep and + * cause pagefault, which makes it pointless to use GFP_NOFS + * or GFP_ATOMIC. + */ + p = kmalloc_track_caller(len + 1, GFP_KERNEL); + if (!p) + return ERR_PTR(-ENOMEM); + + if (copy_from_user(p, src, len)) { + kfree(p); + return ERR_PTR(-EFAULT); + } + p[len] = '\0'; + + return p; +} +EXPORT_SYMBOL(memdup_user_nul); + void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, struct vm_area_struct *prev, struct rb_node *rb_parent) { |