NOMMU: Fix cleanup handling in ramfs_nommu_get_umapped_area()

Fix cleanup handling in ramfs_nommu_get_umapped_area() by only freeing the
number of pages that find_get_pages() said it had returned (nr) rather than
attempting to free the number of pages we asked for (lpages) - thus avoiding
the situation whereby put_page() may be handed NULL pointers if
find_get_pages() returned fewer pages that were requested.

Also avoid a warning about nr being uninitialised and the need for an
if-statement in the cleanup path by using appropriate gotos.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 10 insertions, 11 deletions

diff --git a/fs/ramfs/file-nommu.c b/fs/ramfs/file-nommu.c
index 76acdbc34611..b9b567a28376 100644
--- a/fs/ramfs/file-nommu.c
+++ b/fs/ramfs/file-nommu.c
@@ -262,11 +262,11 @@ unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
         ret = -ENOMEM;
         pages = kzalloc(lpages * sizeof(struct page *), GFP_KERNEL);
         if (!pages)
-                goto out;
+                goto out_free;
 
         nr = find_get_pages(inode->i_mapping, pgoff, lpages, pages);
         if (nr != lpages)
-                goto out; /* leave if some pages were missing */
+                goto out_free_pages; /* leave if some pages were missing */
 
         /* check the pages for physical adjacency */
         ptr = pages;
@@ -274,19 +274,18 @@ unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
         page++;
         for (loop = lpages; loop > 1; loop--)
                 if (*ptr++ != page++)
-                        goto out;
+                        goto out_free_pages;
 
         /* okay - all conditions fulfilled */
         ret = (unsigned long) page_address(pages[0]);
 
- out:
-        if (pages) {
-                ptr = pages;
-                for (loop = lpages; loop > 0; loop--)
-                        put_page(*ptr++);
-                kfree(pages);
-        }
-
+out_free_pages:
+        ptr = pages;
+        for (loop = nr; loop > 0; loop--)
+                put_page(*ptr++);
+out_free:
+        kfree(pages);
+out:
         return ret;
 }