linux-kernel - [PATCH 4.19 096/101] dm integrity: fix deadlock with overlapping I/O

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Message-Id: <20190415183745.448810349@linuxfoundation.org>
Date:   Mon, 15 Apr 2019 20:59:34 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Mikulas Patocka <mpatocka@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>
Subject: [PATCH 4.19 096/101] dm integrity: fix deadlock with overlapping I/O

From: Mikulas Patocka <mpatocka@...hat.com>

commit 4ed319c6ac08e9a28fca7ac188181ac122f4de84 upstream.

dm-integrity will deadlock if overlapping I/O is issued to it, the bug
was introduced by commit 724376a04d1a ("dm integrity: implement fair
range locks").  Users rarely use overlapping I/O so this bug went
undetected until now.

Fix this bug by correcting, likely cut-n-paste, typos in
ranges_overlap() and also remove a flawed ranges_overlap() check in
remove_range_unlocked().  This condition could leave unprocessed bios
hanging on wait_list forever.

Cc: stable@...r.kernel.org # v4.19+
Fixes: 724376a04d1a ("dm integrity: implement fair range locks")
Signed-off-by: Mikulas Patocka <mpatocka@...hat.com>
Signed-off-by: Mike Snitzer <snitzer@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/md/dm-integrity.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -908,7 +908,7 @@ static void copy_from_journal(struct dm_
 static bool ranges_overlap(struct dm_integrity_range *range1, struct dm_integrity_range *range2)
 {
 	return range1->logical_sector < range2->logical_sector + range2->n_sectors &&
-	       range2->logical_sector + range2->n_sectors > range2->logical_sector;
+	       range1->logical_sector + range1->n_sectors > range2->logical_sector;
 }
 
 static bool add_new_range(struct dm_integrity_c *ic, struct dm_integrity_range *new_range, bool check_waiting)
@@ -954,8 +954,6 @@ static void remove_range_unlocked(struct
 		struct dm_integrity_range *last_range =
 			list_first_entry(&ic->wait_list, struct dm_integrity_range, wait_entry);
 		struct task_struct *last_range_task;
-		if (!ranges_overlap(range, last_range))
-			break;
 		last_range_task = last_range->task;
 		list_del(&last_range->wait_entry);
 		if (!add_new_range(ic, last_range, false)) {