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Date:   Wed, 21 Jun 2023 11:33:29 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Arnd Bergmann <arnd@kernel.org>
Cc:     Anil Gurumurthy <anil.gurumurthy@qlogic.com>,
        Sudarsana Kalluru <sudarsana.kalluru@qlogic.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Arnd Bergmann <arnd@arndb.de>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>,
        Bart Van Assche <bvanassche@acm.org>,
        Azeem Shaikh <azeemshaikh38@gmail.com>,
        Krishna Gudipati <kgudipat@brocade.com>,
        James Bottomley <JBottomley@parallels.com>,
        linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
        llvm@lists.linux.dev
Subject: Re: [PATCH 1/2] scsi: bfa: fix function pointer type mismatch for
 hcb_qe->cbfn
Message-ID: <202306211133.DD89F45965@keescook>
References: <20230616092233.3229414-1-arnd@kernel.org>
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On Fri, Jun 16, 2023 at 11:22:09AM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> Some callback functions used here take a boolean argument, others
> take a status argument. This breaks KCFI type checking, so clang
> now warns about the function pointer cast:
> 
> drivers/scsi/bfa/bfad_bsg.c:2138:29: error: cast from 'void (*)(void *, enum bfa_status)' to 'bfa_cb_cbfn_t' (aka 'void (*)(void *, enum bfa_boolean)') converts to incompatible function type [-Werror,-Wcast-function-type-strict]
> 
> Assuming the code is actually correct here and the callers always match
> the argument types of the callee, rework this to replace the explicit
> cast with a union of the two pointer types. This does not change the
> behavior of the code, so if something is actually broken here, a larger
> rework may be necessary.
> 
> Fixes: 37ea0558b87ab ("[SCSI] bfa: Added support to collect and reset fcport stats")
> Fixes: 3ec4f2c8bff25 ("[SCSI] bfa: Added support to configure QOS and collect stats.")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook