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From: Johannes Thumshirn <johannes.thumshirn@wdc.com>
To: axboe@kernel.dk
Cc: linux-block@vger.kernel.org, Changhui Zhong <czhong@redhat.com>,
	Damien Le Moal <dlemoal@kernel.org>,
	Johannes Thumshirn <johannes.thumshirn@wdc.com>
Subject: [PATCH] block: check if zone_wplugs_hash exists in queue_zone_wplugs_show
Date: Thu, 25 Apr 2024 05:02:39 -0700	[thread overview]
Message-ID: <e5fec079dfca448cc21c425cfa5d7b291f5faa67.1714046443.git.johannes.thumshirn@wdc.com> (raw)

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@redhat.com>
Fixes: a98b05b02f0f ("block: Replace zone_wlock debugfs entry with zone_wplugs entry")
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 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


             reply	other threads:[~2024-04-25 12:02 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-25 12:02 Johannes Thumshirn [this message]
2024-04-25 12:14 ` [PATCH] block: check if zone_wplugs_hash exists in queue_zone_wplugs_show Damien Le Moal
2024-04-25 13:48 ` Jens Axboe
2024-04-26  7:42 ` Changhui Zhong

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