CIFS: cifs_read_allocate_pages: don't iterate through whole page array on ENOMEM

commit 31fad7d41e73731f05b8053d17078638cf850fa6 upstream.

 In cifs_read_allocate_pages, in case of ENOMEM, we go through
whole rdata->pages array but we have failed the allocation before
nr_pages, therefore we may end up calling put_page with NULL
pointer, causing oops

Signed-off-by: Roberto Bergantinos Corpas <rbergant@redhat.com>
Acked-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
CC: Stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index e7f1773..df3ee0b 100644 (file)
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2892,7 +2892,9 @@ cifs_read_allocate_pages(struct cifs_readdata *rdata, unsigned int nr_pages)
        }
 
        if (rc) {
-               for (i = 0; i < nr_pages; i++) {
+               unsigned int nr_page_failed = i;
+
+               for (i = 0; i < nr_page_failed; i++) {
                        put_page(rdata->pages[i]);
                        rdata->pages[i] = NULL;
                }