linux-kernel - Re: [for-linus][PATCH 1/2] bootconfig: Fix to check the xbc

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Date:   Tue, 14 Sep 2021 18:11:01 +0200
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Steven Rostedt <rostedt@...dmis.org>, linux-kernel@...r.kernel.org
Cc:     Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        kernel test robot <oliver.sang@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>
Subject: Re: [for-linus][PATCH 1/2] bootconfig: Fix to check the xbc_node is
 used before free it

On 9/14/21 16:48, Steven Rostedt wrote:
> From: Masami Hiramatsu <mhiramat@...nel.org>
> 
> Fix to check the xbc_node is used before calling memblock_free()
> because passing NULL to phys_addr() will cause a panic.
> This will happen if user doesn't pass any bootconfig to the
> kernel, because kernel will call xbc_destroy_all() after
> booting.
> 
> Link: https://lkml.kernel.org/r/163149460533.291098.7342418455457691240.stgit@devnote2
> 
> Fixes: 40caa127f3c7 ("init: bootconfig: Remove all bootconfig data when the init memory is removed")
> Reported-by: kernel test robot <oliver.sang@...el.com>
> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>

Should have replied here.

Tested-by: Vlastimil Babka <vbabka@...e.cz>

details:
https://lore.kernel.org/all/61ab2d0c-3313-aaab-514c-e15b7aa054a0@suse.cz/

> ---
>  lib/bootconfig.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/bootconfig.c b/lib/bootconfig.c
> index f8419cff1147..4f8849706ef6 100644
> --- a/lib/bootconfig.c
> +++ b/lib/bootconfig.c
> @@ -792,7 +792,8 @@ void __init xbc_destroy_all(void)
>  	xbc_data = NULL;
>  	xbc_data_size = 0;
>  	xbc_node_num = 0;
> -	memblock_free(__pa(xbc_nodes), sizeof(struct xbc_node) * XBC_NODE_MAX);
> +	if (xbc_nodes)
> +		memblock_free(__pa(xbc_nodes), sizeof(struct xbc_node) * XBC_NODE_MAX);
>  	xbc_nodes = NULL;
>  	brace_index = 0;
>  }
>