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

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Date:   Mon,  4 Feb 2019 11:36:56 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Pavel Shilovsky <pshilov@...rosoft.com>,
        Steve French <stfrench@...rosoft.com>
Subject: [PATCH 4.20 36/80] CIFS: Fix possible oops and memory leaks in async IO

4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Pavel Shilovsky <pshilov@...rosoft.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@...r.kernel.org>
Signed-off-by: Pavel Shilovsky <pshilov@...rosoft.com>
Signed-off-by: Steve French <stfrench@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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,