releases/4.4.181/cifs-cifs_read_allocate_pages-don-t-iterate-through-whole-page-array-on-enomem.patch

   1 From 31fad7d41e73731f05b8053d17078638cf850fa6 Mon Sep 17 00:00:00 2001
   2 From: Roberto Bergantinos Corpas <rbergant@redhat.com>
   3 Date: Tue, 28 May 2019 09:38:14 +0200
   4 Subject: CIFS: cifs_read_allocate_pages: don't iterate through whole page array on ENOMEM
   5
   6 From: Roberto Bergantinos Corpas <rbergant@redhat.com>
   7
   8 commit 31fad7d41e73731f05b8053d17078638cf850fa6 upstream.
   9
  10  In cifs_read_allocate_pages, in case of ENOMEM, we go through
  11 whole rdata->pages array but we have failed the allocation before
  12 nr_pages, therefore we may end up calling put_page with NULL
  13 pointer, causing oops
  14
  15 Signed-off-by: Roberto Bergantinos Corpas <rbergant@redhat.com>
  16 Acked-by: Pavel Shilovsky <pshilov@microsoft.com>
  17 Signed-off-by: Steve French <stfrench@microsoft.com>
  18 CC: Stable <stable@vger.kernel.org>
  19 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  20
  21 ---
  22  fs/cifs/file.c |    4 +++-
  23  1 file changed, 3 insertions(+), 1 deletion(-)
  24
  25 --- a/fs/cifs/file.c
  26 +++ b/fs/cifs/file.c
  27 @@ -2829,7 +2829,9 @@ cifs_read_allocate_pages(struct cifs_rea
  28         }
  29
  30         if (rc) {
  31 -               for (i = 0; i < nr_pages; i++) {
  32 +               unsigned int nr_page_failed = i;
  33 +
  34 +               for (i = 0; i < nr_page_failed; i++) {
  35                         put_page(rdata->pages[i]);
  36                         rdata->pages[i] = NULL;
  37                 }