[PATCH 4.19 53/73] CIFS: cifs_read_allocate_pages: dont iterate through whole page array on ENOMEM

From: Greg Kroah-Hartman
Date: Fri Jun 07 2019 - 11:49:59 EST


From: Roberto Bergantinos Corpas <rbergant@xxxxxxxxxx>

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@xxxxxxxxxx>
Acked-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
CC: Stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
fs/cifs/file.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2988,7 +2988,9 @@ cifs_read_allocate_pages(struct cifs_rea
}

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;
}