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Wed, 07 Oct 2020 11:39:34 -0700 (PDT) Subject: Re: net: Initialize return value in gro_cells_receive To: Eric Dumazet , Netdev References: <9c6415e4-9d3b-2ba9-494a-c24316ec60c4@gmail.com> <03e2fd9c-e4c9-cff4-90c9-99ea9d3a5713@gmail.com> From: Gregory Rose Message-ID: <00d334dd-6b48-e0e0-bb8d-b643890f4de1@gmail.com> Date: Wed, 7 Oct 2020 11:39:32 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 10/7/2020 9:37 AM, Eric Dumazet wrote: > > > On 10/7/20 5:50 PM, Gregory Rose wrote: >> >> >> On 10/7/2020 1:21 AM, Eric Dumazet wrote: >>> >>> >>> On 10/6/20 8:53 PM, Gregory Rose wrote: >>>> The 'res' return value is uninitalized and may be returned with >>>> some random value.  Initialize to NET_RX_DROP as the default >>>> return value. >>>> >>>> Signed-off-by: Greg Rose >>>> >>>> diff --git a/net/core/gro_cells.c b/net/core/gro_cells.c >>>> index e095fb871d91..4e835960db07 100644 >>>> --- a/net/core/gro_cells.c >>>> +++ b/net/core/gro_cells.c >>>> @@ -13,7 +13,7 @@ int gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb) >>>>   { >>>>          struct net_device *dev = skb->dev; >>>>          struct gro_cell *cell; >>>> -       int res; >>>> +       int res = NET_RX_DROP; >>>> >>>>          rcu_read_lock(); >>>>          if (unlikely(!(dev->flags & IFF_UP))) >>> >>> I do not think this is needed. >>> >>> Also, when/if sending a patch fixing a bug, we require a Fixes: tag. >>> >>> Thanks. >>> >> If it's not needed then feel free to ignore it.  It just looked like >> the unlikely case returns without setting the return value. > > Can you elaborate ? I do not see this problem in current upstream code. > > If a compiler gave you a warning, please give its version, thanks. > No, it's my misreading of the code - it jumps to the drop that is in the middle of an if statement, sets res to NET_RX_DROP there and then jumps to the unlock label. My apologies. - Greg