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-rw-r--r--fs/read_write.c75
1 files changed, 75 insertions, 0 deletions
diff --git a/fs/read_write.c b/fs/read_write.c
index c4f88afbc67f..47c1d4484df9 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -841,6 +841,81 @@ out:
return ret;
}
+#ifdef CONFIG_COMPAT
+ssize_t compat_rw_copy_check_uvector(int type,
+ const struct compat_iovec __user *uvector, unsigned long nr_segs,
+ unsigned long fast_segs, struct iovec *fast_pointer,
+ struct iovec **ret_pointer)
+{
+ compat_ssize_t tot_len;
+ struct iovec *iov = *ret_pointer = fast_pointer;
+ ssize_t ret = 0;
+ int seg;
+
+ /*
+ * SuS says "The readv() function *may* fail if the iovcnt argument
+ * was less than or equal to 0, or greater than {IOV_MAX}. Linux has
+ * traditionally returned zero for zero segments, so...
+ */
+ if (nr_segs == 0)
+ goto out;
+
+ ret = -EINVAL;
+ if (nr_segs > UIO_MAXIOV)
+ goto out;
+ if (nr_segs > fast_segs) {
+ ret = -ENOMEM;
+ iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
+ if (iov == NULL)
+ goto out;
+ }
+ *ret_pointer = iov;
+
+ ret = -EFAULT;
+ if (!access_ok(VERIFY_READ, uvector, nr_segs*sizeof(*uvector)))
+ goto out;
+
+ /*
+ * Single unix specification:
+ * We should -EINVAL if an element length is not >= 0 and fitting an
+ * ssize_t.
+ *
+ * In Linux, the total length is limited to MAX_RW_COUNT, there is
+ * no overflow possibility.
+ */
+ tot_len = 0;
+ ret = -EINVAL;
+ for (seg = 0; seg < nr_segs; seg++) {
+ compat_uptr_t buf;
+ compat_ssize_t len;
+
+ if (__get_user(len, &uvector->iov_len) ||
+ __get_user(buf, &uvector->iov_base)) {
+ ret = -EFAULT;
+ goto out;
+ }
+ if (len < 0) /* size_t not fitting in compat_ssize_t .. */
+ goto out;
+ if (type >= 0 &&
+ !access_ok(vrfy_dir(type), compat_ptr(buf), len)) {
+ ret = -EFAULT;
+ goto out;
+ }
+ if (len > MAX_RW_COUNT - tot_len)
+ len = MAX_RW_COUNT - tot_len;
+ tot_len += len;
+ iov->iov_base = compat_ptr(buf);
+ iov->iov_len = (compat_size_t) len;
+ uvector++;
+ iov++;
+ }
+ ret = tot_len;
+
+out:
+ return ret;
+}
+#endif
+
static ssize_t __do_readv_writev(int type, struct file *file,
struct iov_iter *iter, loff_t *pos, int flags)
{