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Message-ID: <6ba1e424-9903-43db-b567-32a864b896c9@intel.com>
Date:   Tue, 12 Dec 2023 15:05:19 -0800
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH] iavf: Fix null pointer dereference in
 iavf_print_link_message
Content-Language: en-US
To:     Jakub Kicinski <kuba@kernel.org>, Kunwu Chan <chentao@kylinos.cn>
CC:     <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>
References: <20231211025927.233449-1-chentao@kylinos.cn>
 <20231212132851.59054654@kernel.org>
From:   Jesse Brandeburg <jesse.brandeburg@intel.com>
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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

> drivers/net/ethernet/intel/iavf/iavf_virtchnl.c:1425:60: warning: ‘%s’ directive output may be truncated writing 4 bytes into a region of size between 1 and 11 [-Wformat-truncation=]
> drivers/net/ethernet/intel/iavf/iavf_virtchnl.c:1425:17: note: ‘snprintf’ output between 7 and 17 bytes into a destination of size 13

However the original warnings were for "%s" in strings. There should be
a good way, but I don't know it so could use some help.

-Jesse