Changhui reported a kernel crash when running this simple shell
reproducer:
# cd /sys/kernel/debug/block && find . -type f -exec grep -aH . {} \;
The above results in a NULL pointer dereference if a device does not have
a zone_wplugs_hash allocated.
To fix this, return early if we don't have a zone_wplugs_hash.
Reported-by: Changhui Zhong <czhong@xxxxxxxxxx>
Fixes: a98b05b02f0f ("block: Replace zone_wlock debugfs entry with zone_wplugs entry")
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>
---
block/blk-zoned.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index 3a796420f240..bad68277c0b2 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -1774,6 +1774,9 @@ int queue_zone_wplugs_show(void *data, struct seq_file *m)
unsigned int zwp_bio_list_size, i;
unsigned long flags;
+ if (!disk->zone_wplugs_hash)
+ return 0;
+
rcu_read_lock();
for (i = 0; i < disk_zone_wplugs_hash_size(disk); i++) {
hlist_for_each_entry_rcu(zwplug,
--
2.43.0
