linux-kernel - Re: [PATCH] x86/microcode/amd: Add __list_del_entry_valid() in front of __list_del() in free

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Message-ID: <YVMmv5AlKcJeKBkh@infradead.org>
Date:   Tue, 28 Sep 2021 15:29:19 +0100
From:   Christoph Hellwig <hch@...radead.org>
To:     Jiasheng Jiang <jiasheng@...as.ac.cn>
Cc:     bp@...en8.de, tglx@...utronix.de, mingo@...hat.com, x86@...nel.org,
        hpa@...or.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/microcode/amd: Add __list_del_entry_valid() in front
 of __list_del() in free_cache()

On Tue, Sep 28, 2021 at 09:04:44AM +0000, Jiasheng Jiang wrote:
> Directly use __list_del() to remove 'p->plist' might be unsafe,
> as we can see from the __list_del_entry_valid() of 'lib/list_debug.c'
> that p->plist->prev or p->plist->next may be the LIST_POISON,
> or p->list is not a valid double list.
> In that case, __list_del() will be corruption.
> Therefore, we suggest that __list_del_entry_valid()
> should be added in front of the __list_del() in free_cache.

No one should be using list_del directly anyway, so please fix that.