netdev - Re: [PATCH net-next] s390: ism: Pass string literal as format argument of dev_set

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Message-ID: <20250417110814.12521Bf4-hca@linux.ibm.com>
Date: Thu, 17 Apr 2025 13:08:14 +0200
From: Heiko Carstens <hca@...ux.ibm.com>
To: Simon Horman <horms@...nel.org>
Cc: Alexandra Winter <wintera@...ux.ibm.com>,
        Thorsten Winkler <twinkler@...ux.ibm.com>,
        Andrew Lunn <andrew+netdev@...n.ch>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>, netdev@...r.kernel.org,
        linux-s390@...r.kernel.org
Subject: Re: [PATCH net-next] s390: ism: Pass string literal as format
 argument of dev_set_name()

On Thu, Apr 17, 2025 at 11:28:23AM +0100, Simon Horman wrote:
> GCC 14.2.0 reports that passing a non-string literal as the
> format argument of dev_set_name() is potentially insecure.
> 
> drivers/s390/net/ism_drv.c: In function 'ism_probe':
> drivers/s390/net/ism_drv.c:615:2: warning: format not a string literal and no format arguments [-Wformat-security]
>   615 |  dev_set_name(&ism->dev, dev_name(&pdev->dev));
>       |  ^~~~~~~~~~~~
> 
> It seems to me that as pdev is a PCIE device then the dev_name
> call above should always return the device's BDF, e.g. 00:12.0.
> That this should not contain format escape sequences. And thus
> the current usage is safe.
> 
> But, it seems better to be safe than sorry. And, as a bonus, compiler
> output becomes less verbose by addressing this issue.
> 
> Compile tested only.
> No functional change intended.
> 
> Signed-off-by: Simon Horman <horms@...nel.org>
> ---
>  drivers/s390/net/ism_drv.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

It might make sense to say that -Wformat-security was explicitly enabled in
order to trigger this (probably with KCFLAGS=-Wformat-security ?), since this
warning is by default disabled.

Just mentioning this, since I was wondering why I haven't seen this.