Message-ID: <2ee5da4d-7dc5-6624-6c87-133958df6478@linux.vnet.ibm.com>
Date:   Tue, 21 Feb 2023 13:37:29 -0600
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Subject: Re: [PATCH] [v2] scsi: ipr: work around fortify-string warning
To:     Arnd Bergmann <arnd@kernel.org>, Brian King <brking@us.ibm.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        James Bottomley <James.Bottomley@SteelEye.com>
Cc:     Damien Le Moal <damien.lemoal@opensource.wdc.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Kees Cook <keescook@chromium.org>,
        Niklas Cassel <niklas.cassel@wdc.com>,
        John Garry <john.g.garry@oracle.com>,
        linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
        llvm@lists.linux.dev
References: <20230214132831.2118392-1-arnd@kernel.org>
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From:   Brian King <brking@linux.vnet.ibm.com>
In-Reply-To: <20230214132831.2118392-1-arnd@kernel.org>
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On 2/14/23 7:28 AM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> The ipr_log_vpd_compact() function triggers a fortified memcpy() warning
> about a potential string overflow with all versions of clang:
> 
> In file included from drivers/scsi/ipr.c:43:
> In file included from include/linux/string.h:254:
> include/linux/fortify-string.h:520:4: error: call to '__write_overflow_field' declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
>                         __write_overflow_field(p_size_field, size);
>                         ^
> include/linux/fortify-string.h:520:4: error: call to '__write_overflow_field' declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
> 2 errors generated.
> 
> I don't see anything actually wrong with the function, but this is the
> only instance I can reproduce of the fortification going wrong in the
> kernel at the moment, so the easiest solution may be to rewrite the
> function into something that does not trigger the warning.
> 
> Instead of having a combined buffer for vendor/device/serial strings,
> use three separate local variables and just truncate the whitespace
> individually.
> 
> Fixes: 8cf093e275d0 ("[SCSI] ipr: Improved dual adapter errors")
> Cc: Kees Cook <keescook@chromium.org>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Acked-by: Brian King <brking@linux.vnet.ibm.com>

-- 
Brian King
Power Linux I/O
IBM Linux Technology Center