1 files changed, 34 insertions, 3 deletions

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 290b4966004f..18758bcd4dab 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2389,7 +2389,7 @@ cifs_iovec_write(struct file *file, const struct iovec *iov,
                  unsigned long nr_segs, loff_t *poffset)
 {
         unsigned long nr_pages, i;
-        size_t copied, len, cur_len;
+        size_t bytes, copied, len, cur_len;
         ssize_t total_written = 0;
         loff_t offset;
         struct iov_iter it;
@@ -2444,14 +2444,45 @@ cifs_iovec_write(struct file *file, const struct iovec *iov,
 
                 save_len = cur_len;
                 for (i = 0; i < nr_pages; i++) {
-                        copied = min_t(const size_t, cur_len, PAGE_SIZE);
+                        bytes = min_t(const size_t, cur_len, PAGE_SIZE);
                         copied = iov_iter_copy_from_user(wdata->pages[i], &it,
-                                                         0, copied);
+                                                         0, bytes);
                         cur_len -= copied;
                         iov_iter_advance(&it, copied);
+                        /*
+                         * If we didn't copy as much as we expected, then that
+                         * may mean we trod into an unmapped area. Stop copying
+                         * at that point. On the next pass through the big
+                         * loop, we'll likely end up getting a zero-length
+                         * write and bailing out of it.
+                         */
+                        if (copied < bytes)
+                                break;
                 }
                 cur_len = save_len - cur_len;
 
+                /*
+                 * If we have no data to send, then that probably means that
+                 * the copy above failed altogether. That's most likely because
+                 * the address in the iovec was bogus. Set the rc to -EFAULT,
+                 * free anything we allocated and bail out.
+                 */
+                if (!cur_len) {
+                        for (i = 0; i < nr_pages; i++)
+                                put_page(wdata->pages[i]);
+                        kfree(wdata);
+                        rc = -EFAULT;
+                        break;
+                }
+
+                /*
+                 * i + 1 now represents the number of pages we actually used in
+                 * the copy phase above. Bring nr_pages down to that, and free
+                 * any pages that we didn't use.
+                 */
+                for ( ; nr_pages > i + 1; nr_pages--)
+                        put_page(wdata->pages[nr_pages - 1]);
+
                 wdata->sync_mode = WB_SYNC_ALL;
                 wdata->nr_pages = nr_pages;
                 wdata->offset = (__u64)offset;