From: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Date: Thu, 16 Mar 2023 06:55:06 +0000 (+0800)
Subject: dm stats: check for and propagate alloc_percpu failure
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=443c9d522397511a4328dc2ec3c9c63c73049756;p=linux.git

dm stats: check for and propagate alloc_percpu failure

commit d3aa3e060c4a80827eb801fc448debc9daa7c46b upstream.

Check alloc_precpu()'s return value and return an error from
dm_stats_init() if it fails. Update alloc_dev() to fail if
dm_stats_init() does.

Otherwise, a NULL pointer dereference will occur in dm_stats_cleanup()
even if dm-stats isn't being actively used.

Fixes: fd2ed4d25270 ("dm: add statistics support")
Cc: stable@vger.kernel.org
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c
index a3f2050b9c9b4..9f71d169587f5 100644
--- a/drivers/md/dm-stats.c
+++ b/drivers/md/dm-stats.c
@@ -188,7 +188,7 @@ static int dm_stat_in_flight(struct dm_stat_shared *shared)
 	       atomic_read(&shared->in_flight[WRITE]);
 }
 
-void dm_stats_init(struct dm_stats *stats)
+int dm_stats_init(struct dm_stats *stats)
 {
 	int cpu;
 	struct dm_stats_last_position *last;
@@ -197,11 +197,16 @@ void dm_stats_init(struct dm_stats *stats)
 	INIT_LIST_HEAD(&stats->list);
 	stats->precise_timestamps = false;
 	stats->last = alloc_percpu(struct dm_stats_last_position);
+	if (!stats->last)
+		return -ENOMEM;
+
 	for_each_possible_cpu(cpu) {
 		last = per_cpu_ptr(stats->last, cpu);
 		last->last_sector = (sector_t)ULLONG_MAX;
 		last->last_rw = UINT_MAX;
 	}
+
+	return 0;
 }
 
 void dm_stats_cleanup(struct dm_stats *stats)
diff --git a/drivers/md/dm-stats.h b/drivers/md/dm-stats.h
index 09c81a1ec057d..ee32b099f1cf7 100644
--- a/drivers/md/dm-stats.h
+++ b/drivers/md/dm-stats.h
@@ -21,7 +21,7 @@ struct dm_stats_aux {
 	unsigned long long duration_ns;
 };
 
-void dm_stats_init(struct dm_stats *st);
+int dm_stats_init(struct dm_stats *st);
 void dm_stats_cleanup(struct dm_stats *st);
 
 struct mapped_device;
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 0bd2185d5194e..8bc121d394471 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1818,7 +1818,9 @@ static struct mapped_device *alloc_dev(int minor)
 	if (!md->pending_io)
 		goto bad;
 
-	dm_stats_init(&md->stats);
+	r = dm_stats_init(&md->stats);
+	if (r < 0)
+		goto bad;
 
 	/* Populate the mapping, nobody knows we exist yet */
 	spin_lock(&_minor_lock);