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>

diff --git a/fs/ramfs/file-nommu.c b/fs/ramfs/file-nommu.c
index 76acdbc..b9b567a 100644 (file)
--- 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;
 }