linux-kernel - Re: [PATCH] boot: simple_alloc: check after increasing memory allocation

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Date:   Mon, 19 Dec 2022 06:42:53 +0000
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Li zeming <zeming@...china.com>,
        "mpe@...erman.id.au" <mpe@...erman.id.au>,
        "npiggin@...il.com" <npiggin@...il.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
CC:     "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] boot: simple_alloc: check after increasing memory
 allocation



Le 19/12/2022 à 03:18, Li zeming a écrit :
> The pointer new adds judgment and should help with program robustness.

This text is not understandable.

Do you mean:

simple_malloc() will return NULL when there is now enough memory left.
Check pointer 'new' before using it to copy the old data.

> 
> Signed-off-by: Li zeming <zeming@...china.com>
> ---
>   arch/powerpc/boot/simple_alloc.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/boot/simple_alloc.c b/arch/powerpc/boot/simple_alloc.c
> index 267d6524caac..db9aaa5face3 100644
> --- a/arch/powerpc/boot/simple_alloc.c
> +++ b/arch/powerpc/boot/simple_alloc.c
> @@ -112,7 +112,9 @@ static void *simple_realloc(void *ptr, unsigned long size)
>   		return ptr;
>   
>   	new = simple_malloc(size);
> -	memcpy(new, ptr, p->size);
> +	if (new)
> +		memcpy(new, ptr, p->size);
> +
>   	simple_free(ptr);
>   	return new;
>   }