Re: [syzbot] [block?] general protection fault in bio_first_folio

[syzbot <syzbot+8b23309d5788a79d3eea@syzkaller.appspotmail.com>]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org.

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Subject: [block?] general protection fault in bio_first_folio
Author: eadavis@qq.com

please test general protection fault in bio_first_folio

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git abb240f7a2bd

diff --git a/block/blk-map.c b/block/blk-map.c
index 8584babf3ea0..6c6f0ef1407b 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -344,7 +344,8 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
 	return 0;
 
  out_unmap:
-	bio_release_pages(bio, false);
+	if (bio->bi_vcnt)
+		bio_release_pages(bio, false);
 	blk_mq_map_bio_put(bio);
 	return ret;
 }