From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
To: Dan Carpenter <dan.carpenter@oracle.com>,
Sandro Volery <sandro@volery.com>
Cc: devel@driverdev.osuosl.org, gregkh@linuxfoundation.org,
aaro.koskinen@iki.fi, davem@davemloft.net,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Staging: octeon: Avoid several usecases of strcpy
Date: Wed, 11 Sep 2019 12:58:14 +0200 [thread overview]
Message-ID: <7a004f18-50cd-9ab0-40b0-051624f0fb95@rasmusvillemoes.dk> (raw)
In-Reply-To: <20190911091659.GI15977@kadam>
On 11/09/2019 11.16, Dan Carpenter wrote:
> On Wed, Sep 11, 2019 at 11:04:38AM +0200, Sandro Volery wrote:
>>
>>
>>> On 11 Sep 2019, at 10:52, Dan Carpenter <dan.carpenter@oracle.com> wrote:
>>>
>>> On Wed, Sep 11, 2019 at 08:23:59AM +0200, Sandro Volery wrote:
>>>> strcpy was used multiple times in strcpy to write into dev->name.
>>>> I replaced them with strscpy.
Yes, that's obviously what the patch does. The commit log is supposed to
explain _why_.
>>>> Signed-off-by: Sandro Volery <sandro@volery.com>
>>>> ---
>>>> drivers/staging/octeon/ethernet.c | 16 ++++++++--------
>>>> 1 file changed, 8 insertions(+), 8 deletions(-)
>>>>
>>>> diff --git a/drivers/staging/octeon/ethernet.c b/drivers/staging/octeon/ethernet.c
>>>> index 8889494adf1f..cf8e9a23ebf9 100644
>>>> --- a/drivers/staging/octeon/ethernet.c
>>>> +++ b/drivers/staging/octeon/ethernet.c
>>>> @@ -784,7 +784,7 @@ static int cvm_oct_probe(struct platform_device *pdev)
>>>> priv->imode = CVMX_HELPER_INTERFACE_MODE_DISABLED;
>>>> priv->port = CVMX_PIP_NUM_INPUT_PORTS;
>>>> priv->queue = -1;
>>>> - strcpy(dev->name, "pow%d");
>>>> + strscpy(dev->name, "pow%d", sizeof(dev->name));
>>>
>>> Is there a program which is generating a warning for this code? We know
>>> that "pow%d" is 6 characters and static analysis tools can understand
>>> this code fine so we know it's safe.
>>
>> Well I was confused too but checkpatch complained about
>> it so I figured I'd clean it up quick
>
> Ah. It's a new checkpatch warning. I don't care in that case. I'm
> fine with replacing all of these in that case.
But why? It actually gives _less_ compile-time checking (gcc and all
static tools know perfectly well what strcpy is and does, but knows
nothing of strscpy). And using sizeof() instead of ARRAY_SIZE() means a
future reader is not even sure dev->name is not just a pointer.
Moreover, it's very likely also a runtime and .text pessimization, again
because gcc knows what strcpy does, so it can just do a few immediate
stores (e.g. 0x25776f70 for the "pow%" part) instead of emitting an
actual function call.
Rasmus
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prev parent reply other threads:[~2019-09-11 10:58 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-11 6:23 [PATCH] Staging: octeon: Avoid several usecases of strcpy Sandro Volery
2019-09-11 8:49 ` Dan Carpenter
2019-09-11 9:04 ` Sandro Volery
2019-09-11 9:16 ` Dan Carpenter
2019-09-11 9:21 ` Sandro Volery
2019-09-11 10:05 ` Dan Carpenter
2019-09-11 10:58 ` Rasmus Villemoes [this message]
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