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Date: Sun, 8 Aug 2021 19:06:30 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Bernd Petrovitsch <bernd@...rovitsch.priv.at>,
Len Baker <len.baker@....com>, Andy Gross <agross@...nel.org>,
Bjorn Andersson <bjorn.andersson@...aro.org>,
Geert Uytterhoeven <geert+renesas@...der.be>,
Magnus Damm <magnus.damm@...il.com>,
Santosh Shilimkar <ssantosh@...nel.org>
Cc: Kees Cook <keescook@...omium.org>,
David Laight <David.Laight@...LAB.COM>,
Robin Murphy <robin.murphy@....com>,
linux-hardening@...r.kernel.org, linux-arm-msm@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v4 2/3] drivers/soc/renesas: Prefer memcpy over strcpy
Hi,
Le 08/08/2021 à 17:35, Bernd Petrovitsch a écrit :
> Hi all!
>
> On 08/08/2021 14:50, Len Baker wrote:
>> strcpy() performs no bounds checking on the destination buffer. This
>> could result in linear overflows beyond the end of the buffer, leading
>> to all kinds of misbehaviors. So, use memcpy() as a safe replacement.
>>
>> This is a previous step in the path to remove the strcpy() function
>> entirely from the kernel.
>>
>> Signed-off-by: Len Baker <len.baker@....com>
>> ---
>> drivers/soc/renesas/r8a779a0-sysc.c | 6 ++++--
>> drivers/soc/renesas/rcar-sysc.c | 6 ++++--
>> 2 files changed, 8 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/soc/renesas/r8a779a0-sysc.c b/drivers/soc/renesas/r8a779a0-sysc.c
>> index d464ffa1be33..7410b9fa9846 100644
>> --- a/drivers/soc/renesas/r8a779a0-sysc.c
>> +++ b/drivers/soc/renesas/r8a779a0-sysc.c
>> @@ -404,19 +404,21 @@ static int __init r8a779a0_sysc_pd_init(void)
>> for (i = 0; i < info->num_areas; i++) {
>> const struct r8a779a0_sysc_area *area = &info->areas[i];
>> struct r8a779a0_sysc_pd *pd;
>> + size_t n;
>>
>> if (!area->name) {
>> /* Skip NULLified area */
>> continue;
>> }
>>
>> - pd = kzalloc(sizeof(*pd) + strlen(area->name) + 1, GFP_KERNEL);
>> + n = strlen(area->name) + 1;
>> + pd = kzalloc(sizeof(*pd) + n, GFP_KERNEL);
> Zeroing the allocated bytes is not needed since it's completly
> overwritten with the strcpy()/memcpy().
The strcpy()/memcpy() only overwrites the pd->name field, not the whole
pd structure.
I think that it is needed to keep the kzalloc.
Just my 2c,
CJ
>> if (!pd) {
>> error = -ENOMEM;
>> goto out_put;
>> }
>>
>> - strcpy(pd->name, area->name);
>> + memcpy(pd->name, area->name, n);
>> pd->genpd.name = pd->name;
>> pd->pdr = area->pdr;
>> pd->flags = area->flags;
>
> And similar for the second hunk.
>
> MfG,
> Bernd
>
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