[PATCH 4.20 36/80] CIFS: Fix possible oops and memory leaks in async IO

Greg Kroah-Hartman
2019-02-04T10:52:52Z

From: Pavel Shilovsky <pshilov@microsoft.com>

commit 9bda8723da2d55b1de833b98cf802b88006e5b69 upstream.

Allocation of a page array for non-cached IO was separated from
allocation of rdata and wdata structures and this introduced memory
leaks and a possible null pointer dereference. This patch fixes
these problems.

Cc: <stable@vger.kernel.org>
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/cifs/file.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2670,6 +2670,7 @@ cifs_write_from_iter(loff_t offset, size

rc = cifs_write_allocate_pages(wdata->pages, nr_pages);
if (rc) {
+ kvfree(wdata->pages);
kfree(wdata);
add_credits_and_wake_if(server, credits, 0);
break;
@@ -2681,6 +2682,7 @@ cifs_write_from_iter(loff_t offset, size
if (rc) {
for (i = 0; i < nr_pages; i++)
put_page(wdata->pages[i]);
+ kvfree(wdata->pages);
kfree(wdata);
add_credits_and_wake_if(server, credits, 0);
break;
@@ -3360,8 +3362,12 @@ cifs_send_async_read(loff_t offset, size
}

rc = cifs_read_allocate_pages(rdata, npages);
- if (rc)
- goto error;
+ if (rc) {
+ kvfree(rdata->pages);
+ kfree(rdata);
+ add_credits_and_wake_if(server, credits, 0);
+ break;
+ }

rdata->tailsz = PAGE_SIZE;
}
@@ -3381,7 +3387,6 @@ cifs_send_async_read(loff_t offset, size
if (!rdata->cfile->invalidHandle ||
!(rc = cifs_reopen_file(rdata->cfile, true)))
rc = server->ops->async_readv(rdata);
-error:
if (rc) {
add_credits_and_wake_if(server, rdata->credits, 0);
kref_put(&rdata->refcount,