linux-kernel - Re: [PATCH V3] bcache: revert replacing IS_ERR_OR_NULL with IS

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Message-Id: <7B52DB03-5E27-4F61-AE1A-11081B12E4BE@suse.de>
Date: Wed, 27 Nov 2024 11:17:01 +0800
From: Coly Li <colyli@...e.de>
To: liequan che <liequanche@...il.com>
Cc: "mingzhe.zou@...ystack.cn" <mingzhe.zou@...ystack.cn>,
 Kent Overstreet <kent.overstreet@...il.com>,
 linux-bcache <linux-bcache@...r.kernel.org>,
 linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V3] bcache: revert replacing IS_ERR_OR_NULL with IS_ERR
 again



> 2024年11月27日 11:01，liequan che <liequanche@...il.com> 写道：
> 
> Commit 028ddcac477b ("bcache: Remove unnecessary NULL point check in
> node allocations") leads a NULL pointer deference in cache_set_flush().
> 
> 1721         if (!IS_ERR_OR_NULL(c->root))
> 1722                 list_add(&c->root->list, &c->btree_cache);
> 
> From the above code in cache_set_flush(), if previous registration code
> fails before allocating c->root, it is possible c->root is NULL as what
> it is initialized. Also __bch_btree_node_alloc() never returns NULL but
> c->root is possible to be NULL at above line 1721.
> 
> This patch replaces IS_ERR() by IS_ERR_OR_NULL() to fix this.


OK, this time the commit log makes a lot sense. It is clear to me.


> 
> Fixes: 028ddcac477b ("bcache: Remove unnecessary NULL point check in
> node allocations")
> Signed-off-by: Liequan Che <cheliequan@...pur.com>
> Cc: stable@...r.kernel.org
> Cc: Zheng Wang <zyytlz.wz@....com>
> Cc: Coly Li <colyli@...e.de>
> ---
> drivers/md/bcache/super.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> index e7abfdd77c3b..e42f1400cea9 100644
> --- a/drivers/md/bcache/super.c
> +++ b/drivers/md/bcache/super.c
> @@ -1718,7 +1718,7 @@ static CLOSURE_CALLBACK(cache_set_flush)
>        if (!IS_ERR_OR_NULL(c->gc_thread))
>                kthread_stop(c->gc_thread);
> 
> -       if (!IS_ERR(c->root))
> +       if (!IS_ERR_OR_NULL(c->root))
>                list_add(&c->root->list, &c->btree_cache);
> 
>        /*
> —
> 2.46.0

It is fine to me. I am in travel these days, and will handle this patch by end of this week.

Thanks for composing this patch.

Coly Li