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[75.142.250.213]) by smtp.gmail.com with ESMTPSA id r5sm136684qtd.87.2020.08.24.14.31.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 24 Aug 2020 14:31:03 -0700 (PDT) Subject: Re: [PATCH v2] usb: storage: initialize variable To: Vito Caputo Cc: stern@rowland.harvard.edu, gregkh@linuxfoundation.org, linux-usb@vger.kernel.org, usb-storage@lists.one-eyed-alien.net, linux-kernel@vger.kernel.org References: <20200824211027.11543-1-trix@redhat.com> <20200824211839.6c7m7yhgd7ffq3g3@shells.gnugeneration.com> From: Tom Rix Message-ID: Date: Mon, 24 Aug 2020 14:31:01 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200824211839.6c7m7yhgd7ffq3g3@shells.gnugeneration.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On 8/24/20 2:18 PM, Vito Caputo wrote: > On Mon, Aug 24, 2020 at 02:10:27PM -0700, trix@redhat.com wrote: >> From: Tom Rix >> >> clang static analysis reports this representative problem >> >> transport.c:495:15: warning: Assigned value is garbage or >> undefined >> length_left -= partial; >> ^ ~~~~~~~ >> partial is set only when usb_stor_bulk_transfer_sglist() >> is successful. >> >> So set partial on entry to 0. >> >> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") >> Signed-off-by: Tom Rix >> --- >> drivers/usb/storage/transport.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/drivers/usb/storage/transport.c b/drivers/usb/storage/transport.c >> index 238a8088e17f..044429717dcc 100644 >> --- a/drivers/usb/storage/transport.c >> +++ b/drivers/usb/storage/transport.c >> @@ -414,6 +414,9 @@ static int usb_stor_bulk_transfer_sglist(struct us_data *us, unsigned int pipe, >> { >> int result; >> >> + if (act_len) >> + *act_len = 0; >> + >> /* don't submit s-g requests during abort processing */ >> if (test_bit(US_FLIDX_ABORTING, &us->dflags)) >> return USB_STOR_XFER_ERROR; > At a glance this seems odd to me. If the caller insists on ignoring > the return value, shouldn't it just initialize partial to zero? > > In my experience it's generally frowned upon for functions to store > results in error paths. Then maybe v1 is more appropriate. Else i can spin a v3. My preference is v1 as it doesn't add any runtime if-checks. Tom > Regards, > Vito Caputo >