diff options
Diffstat (limited to 'fs/read_write.c')
| -rw-r--r-- | fs/read_write.c | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/fs/read_write.c b/fs/read_write.c index 66215a7b17cf..190e0d362581 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -730,6 +730,35 @@ static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter, /* A write operation does a read from user space and vice versa */ #define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ) +/** + * rw_copy_check_uvector() - Copy an array of &struct iovec from userspace + * into the kernel and check that it is valid. + * + * @type: One of %CHECK_IOVEC_ONLY, %READ, or %WRITE. + * @uvector: Pointer to the userspace array. + * @nr_segs: Number of elements in userspace array. + * @fast_segs: Number of elements in @fast_pointer. + * @fast_pointer: Pointer to (usually small on-stack) kernel array. + * @ret_pointer: (output parameter) Pointer to a variable that will point to + * either @fast_pointer, a newly allocated kernel array, or NULL, + * depending on which array was used. + * + * This function copies an array of &struct iovec of @nr_segs from + * userspace into the kernel and checks that each element is valid (e.g. + * it does not point to a kernel address or cause overflow by being too + * large, etc.). + * + * As an optimization, the caller may provide a pointer to a small + * on-stack array in @fast_pointer, typically %UIO_FASTIOV elements long + * (the size of this array, or 0 if unused, should be given in @fast_segs). + * + * @ret_pointer will always point to the array that was used, so the + * caller must take care not to call kfree() on it e.g. in case the + * @fast_pointer array was used and it was allocated on the stack. + * + * Return: The total number of bytes covered by the iovec array on success + * or a negative error code on error. + */ ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector, unsigned long nr_segs, unsigned long fast_segs, struct iovec *fast_pointer, |