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 <stable@xxxxxxxxxxxxxxx> know about it. >From 899f0429c7d3eed886406cd72182bee3b96aa1f9 Mon Sep 17 00:00:00 2001 From: Andreas Gruenbacher <agruenba@xxxxxxxxxx> Date: Mon, 9 Oct 2017 11:13:18 +0200 Subject: direct-io: Prevent NULL pointer access in submit_page_section From: Andreas Gruenbacher <agruenba@xxxxxxxxxx> 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. Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/direct-io.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -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 agruenba@xxxxxxxxxx are queue-4.9/direct-io-prevent-null-pointer-access-in-submit_page_section.patch