From: Jiasheng Jiang jiasheng@iscas.ac.cn
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 --- drivers/md/dm-stats.c | 7 ++++++- drivers/md/dm-stats.h | 2 +- drivers/md/dm.c | 4 +++- 3 files changed, 10 insertions(+), 3 deletions(-)
--- a/drivers/md/dm-stats.c +++ b/drivers/md/dm-stats.c @@ -188,7 +188,7 @@ static int dm_stat_in_flight(struct dm_s 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; @@ -196,11 +196,16 @@ void dm_stats_init(struct dm_stats *stat mutex_init(&stats->mutex); INIT_LIST_HEAD(&stats->list); 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) --- a/drivers/md/dm-stats.h +++ b/drivers/md/dm-stats.h @@ -22,7 +22,7 @@ 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; --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -2021,7 +2021,9 @@ static struct mapped_device *alloc_dev(i bio_set_dev(&md->flush_bio, md->bdev); md->flush_bio.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC;
- 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);