Patch "direct-io: Prevent NULL pointer access in submit_page_section" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

direct-io: Prevent NULL pointer access in submit_page_section

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
direct-io-prevent-null-pointer-access-in-submit_page_section.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Andreas Gruenbacher <[email protected]>
Date: Mon, 9 Oct 2017 11:13:18 +0200
Subject: direct-io: Prevent NULL pointer access in submit_page_section

From: Andreas Gruenbacher <[email protected]>

commit 899f0429c7d3eed886406cd72182bee3b96aa1f9 upstream.

In the code added to function submit_page_section by commit b1058b981, sdio->bio can currently be NULL when calling dio_bio_submit. This then leads to a NULL pointer access in dio_bio_submit, so check for a NULL bio in submit_page_section before trying to submit it instead.

Fixes xfstest generic/250 on gfs2.

---
 fs/direct-io.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

@@ -835,7 +835,8 @@ out:
 	 */
 	if (sdio->boundary) {
 		ret = dio_send_cur_page(dio, sdio, map_bh);
-		dio_bio_submit(dio, sdio);
+		if (sdio->bio)
+			dio_bio_submit(dio, sdio);
 		put_page(sdio->cur_page);
 		sdio->cur_page = NULL;
 	}

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/direct-io-prevent-null-pointer-access-in-submit_page_section.patch