[PATCH 5.0 114/117] dm integrity: fix deadlock with overlapping I/O

Greg Kroah-Hartman
2019-04-15T19:14:32Z

From: Mikulas Patocka <mpatocka@redhat.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@vger.kernel.org # v4.19+
Fixes: 724376a04d1a ("dm integrity: implement fair range locks")
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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
@@ -913,7 +913,7 @@ 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)
@@ -959,8 +959,6 @@ 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)) {