linux-kernel - Re: [PATCH] ubifs: fix possible dereference after free

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Message-ID: <939c0385-8663-91a2-df20-920f264a2aa1@huawei.com>
Date:   Wed, 6 Sep 2023 09:42:27 +0800
From:   Zhihao Cheng <chengzhihao1@...wei.com>
To:     Konstantin Meskhidze <konstantin.meskhidze@...wei.com>,
        <richard@....at>
CC:     <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <yusongping@...wei.com>, <artem.kuzin@...wei.com>
Subject: Re: [PATCH] ubifs: fix possible dereference after free

在 2023/9/5 18:12, Konstantin Meskhidze 写道:
> 'old_idx' could be dereferenced after free via 'rb_link_node' function
> call.
> 
> Fixes: b5fda08ef213 ("ubifs: Fix memleak when insert_old_idx() failed")
> Co-developed-by: Ivanov Mikhail <ivanov.mikhail1@...wei-partners.com>
> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
> ---
>   fs/ubifs/tnc.c | 1 +
>   1 file changed, 1 insertion(+)
> 

Only for static alarms，although it couldn't happen in theory.

Reviewed-by: Zhihao Cheng <chengzhihao1@...wei.com>

> diff --git a/fs/ubifs/tnc.c b/fs/ubifs/tnc.c
> index 6b7d95b65f4b..f4728e65d1bd 100644
> --- a/fs/ubifs/tnc.c
> +++ b/fs/ubifs/tnc.c
> @@ -64,8 +64,9 @@ static void do_insert_old_idx(struct ubifs_info *c,
>   			p = &(*p)->rb_right;
>   		else {
>   			ubifs_err(c, "old idx added twice!");
>   			kfree(old_idx);
> +			return;
>   		}
>   	}
>   	rb_link_node(&old_idx->rb, parent, p);
>   	rb_insert_color(&old_idx->rb, &c->old_idx);
>