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From: Jakub Kicinski <kuba@kernel.org>
To: Jesse Brandeburg <jesse.brandeburg@intel.com>
Cc: Kunwu Chan <chentao@kylinos.cn>,
	Kunwu Chan <kunwu.chan@hotmail.com>,
	przemyslaw.kitszel@intel.com, linux-kernel@vger.kernel.org,
	edumazet@google.com, anthony.l.nguyen@intel.com,
	netdev@vger.kernel.org, jacob.e.keller@intel.com,
	intel-wired-lan@lists.osuosl.org, pabeni@redhat.com,
	davem@davemloft.net
Subject: Re: [Intel-wired-lan] [PATCH] iavf: Fix null pointer dereference in iavf_print_link_message
Date: Tue, 12 Dec 2023 15:20:20 -0800	[thread overview]
Message-ID: <20231212152020.4a24b2f7@kernel.org> (raw)
In-Reply-To: <6ba1e424-9903-43db-b567-32a864b896c9@intel.com>

On Tue, 12 Dec 2023 15:05:19 -0800 Jesse Brandeburg wrote:
> On 12/12/2023 1:28 PM, Jakub Kicinski wrote:
> > On Mon, 11 Dec 2023 10:59:27 +0800 Kunwu Chan wrote:  
> >> kasprintf() returns a pointer to dynamically allocated memory
> >> which can be NULL upon failure.
> >>
> >> Fixes: 1978d3ead82c ("intel: fix string truncation warnings")  
> > 
> > No need for the allocation here, print to a buffer on the stack.  
> 
> Sure, but I think that just takes us full circle back to where we
> started. reverting this to the previous code will add back W=1 warnings.
> 
> The whole point of the commit mentioned above was to get a reasonable
> implementation that won't cause string truncation warnings. Is there
> some trick I don't know about to get an allocation which will not
> trigger snprintf and friends to print warnings from -Wformat-truncation

Hm, it'd be nice if there was a flavor of snprintf which explicitly
doesn't trigger this warning. Or perhaps a marking for the output
buffer that says "truncation OK".

Absent that, can we print to a buffer on the stack and copy?
The link message is probably meh, but automation may get quite
confused if a NIC suddenly stops reporting FW version..
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WARNING: multiple messages have this Message-ID (diff)
From: Jakub Kicinski <kuba@kernel.org>
To: Jesse Brandeburg <jesse.brandeburg@intel.com>
Cc: Kunwu Chan <chentao@kylinos.cn>, <anthony.l.nguyen@intel.com>,
	<davem@davemloft.net>, <edumazet@google.com>, <pabeni@redhat.com>,
	<jacob.e.keller@intel.com>, <przemyslaw.kitszel@intel.com>,
	<intel-wired-lan@lists.osuosl.org>, <netdev@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>,
	Kunwu Chan <kunwu.chan@hotmail.com>
Subject: Re: [PATCH] iavf: Fix null pointer dereference in iavf_print_link_message
Date: Tue, 12 Dec 2023 15:20:20 -0800	[thread overview]
Message-ID: <20231212152020.4a24b2f7@kernel.org> (raw)
In-Reply-To: <6ba1e424-9903-43db-b567-32a864b896c9@intel.com>

On Tue, 12 Dec 2023 15:05:19 -0800 Jesse Brandeburg wrote:
> On 12/12/2023 1:28 PM, Jakub Kicinski wrote:
> > On Mon, 11 Dec 2023 10:59:27 +0800 Kunwu Chan wrote:  
> >> kasprintf() returns a pointer to dynamically allocated memory
> >> which can be NULL upon failure.
> >>
> >> Fixes: 1978d3ead82c ("intel: fix string truncation warnings")  
> > 
> > No need for the allocation here, print to a buffer on the stack.  
> 
> Sure, but I think that just takes us full circle back to where we
> started. reverting this to the previous code will add back W=1 warnings.
> 
> The whole point of the commit mentioned above was to get a reasonable
> implementation that won't cause string truncation warnings. Is there
> some trick I don't know about to get an allocation which will not
> trigger snprintf and friends to print warnings from -Wformat-truncation

Hm, it'd be nice if there was a flavor of snprintf which explicitly
doesn't trigger this warning. Or perhaps a marking for the output
buffer that says "truncation OK".

Absent that, can we print to a buffer on the stack and copy?
The link message is probably meh, but automation may get quite
confused if a NIC suddenly stops reporting FW version..

  reply	other threads:[~2023-12-12 23:20 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-12-11  2:59 [Intel-wired-lan] [PATCH] iavf: Fix null pointer dereference in iavf_print_link_message Kunwu Chan
2023-12-11  2:59 ` Kunwu Chan
2023-12-12 21:28 ` [Intel-wired-lan] " Jakub Kicinski
2023-12-12 21:28   ` Jakub Kicinski
2023-12-12 23:05   ` [Intel-wired-lan] " Jesse Brandeburg
2023-12-12 23:05     ` Jesse Brandeburg
2023-12-12 23:20     ` Jakub Kicinski [this message]
2023-12-12 23:20       ` Jakub Kicinski
2023-12-14  6:46   ` [Intel-wired-lan] " Kunwu Chan
2023-12-14  6:46     ` Kunwu Chan

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