From: Changhui Zhong <czhong@redhat.com>
To: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Cc: axboe@kernel.dk, linux-block@vger.kernel.org,
Damien Le Moal <dlemoal@kernel.org>
Subject: Re: [PATCH] block: check if zone_wplugs_hash exists in queue_zone_wplugs_show
Date: Fri, 26 Apr 2024 15:42:49 +0800 [thread overview]
Message-ID: <CAGVVp+UyW8a8MNeet66UWUhgB0+gBWCh=_wbN=18tpbQO6_EKg@mail.gmail.com> (raw)
In-Reply-To: <e5fec079dfca448cc21c425cfa5d7b291f5faa67.1714046443.git.johannes.thumshirn@wdc.com>
On Thu, Apr 25, 2024 at 8:02 PM Johannes Thumshirn
<johannes.thumshirn@wdc.com> wrote:
>
> 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
>
>
Verified the panic issue was fixed by this patch,
Tested-by: Changhui Zhong <czhong@redhat.com>
prev parent reply other threads:[~2024-04-26 7:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-25 12:02 [PATCH] block: check if zone_wplugs_hash exists in queue_zone_wplugs_show Johannes Thumshirn
2024-04-25 12:14 ` Damien Le Moal
2024-04-25 13:48 ` Jens Axboe
2024-04-26 7:42 ` Changhui Zhong [this message]
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