dm stats: check for and propagate alloc_percpu failure

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>

diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c
index c21a19ab73f705d791e611101e79b467fe329bf0..db2d997a6c1815ce6f7f72fa0fed51572afae856 100644 (file)
--- 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 0bc152c8e4f310282845a30d65a0528d029af254..c6728c8b41594bd1a9cac425be013d8a03f085d3 100644 (file)
--- 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 eace45a18d45611e70e1b4a988d674535925a30a..b6ace995b9ca3d22ca6c76264ab38db35326675a 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2097,7 +2097,9 @@ 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);