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[72.194.116.95]) by smtp.gmail.com with ESMTPSA id g15-20020aa7818f000000b00505ce2e4640sm6678733pfi.100.2022.04.16.12.38.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 16 Apr 2022 12:38:38 -0700 (PDT) Message-ID: <64a9fc32-0288-d142-f35b-0f688a0a6659@gmail.com> Date: Sat, 16 Apr 2022 12:38:35 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH net-next v4 06/18] net: dsa: mv88e6xxx: refactor mv88e6xxx_port_vlan() Content-Language: en-US To: Jakob Koschel , "David S. Miller" Cc: Jakub Kicinski , Paolo Abeni , Andrew Lunn , Vivien Didelot , Vladimir Oltean , Lars Povlsen , Steen Hegelund , UNGLinuxDriver@microchip.com, Ariel Elior , Manish Chopra , Edward Cree , Martin Habets , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Jiri Pirko , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Casper Andersson , Bjarni Jonasson , Christophe JAILLET , Arnd Bergmann , Colin Ian King , Eric Dumazet , Xu Wang , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, bpf@vger.kernel.org, Mike Rapoport , Brian Johannesmeyer , Cristiano Giuffrida , "Bos, H.J." , Vladimir Oltean References: <20220415122947.2754662-1-jakobkoschel@gmail.com> <20220415122947.2754662-7-jakobkoschel@gmail.com> From: Florian Fainelli In-Reply-To: <20220415122947.2754662-7-jakobkoschel@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/15/2022 5:29 AM, Jakob Koschel wrote: > From: Vladimir Oltean > > To avoid bugs and speculative execution exploits due to type-confused > pointers at the end of a list_for_each_entry() loop, one measure is to > restrict code to not use the iterator variable outside the loop block. > > In the case of mv88e6xxx_port_vlan(), this isn't a problem, as we never > let the loops exit through "natural causes" anyway, by using a "found" > variable and then using the last "dp" iterator prior to the break, which > is a safe thing to do. > > Nonetheless, with the expected new syntax, this pattern will no longer > be possible. > > Profit off of the occasion and break the two port finding methods into > smaller sub-functions. Somehow, returning a copy of the iterator pointer > is still accepted. > > This change makes it redundant to have a "bool found", since the "dp" > from mv88e6xxx_port_vlan() now holds NULL if we haven't found what we > were looking for. > > Signed-off-by: Vladimir Oltean > Signed-off-by: Jakob Koschel Reviewed-by: Florian Fainelli -- Florian