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Message ID 20171009091231.26623-1-agruenba@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Andreas Gruenbacher Oct. 9, 2017, 9:12 a.m. UTC
Date: Wed, 4 Oct 2017 23:09:38 +0200
Subject: [PATCH] direct-io: Prevent NULL pointer access in submit_page_section

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@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
 fs/direct-io.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
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diff --git a/fs/direct-io.c b/fs/direct-io.c
index 5fa2211e49ae..e0332da392d8 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -838,7 +838,8 @@  submit_page_section(struct dio *dio, struct dio_submit *sdio, struct page *page,
 	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);
 		sdio->cur_page = NULL;