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Wed, 02 Sep 2026 12:53:04 -0700 (PDT) From: Yaroslav Dudkov To: Ido Schimmel Cc: netdev@vger.kernel.org, davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com, dsahern@kernel.org, horms@kernel.org, aconole@redhat.com, sbrivio@redhat.com, gnault@redhat.com, laikabcprice@gmail.com, rough.rock3059@datachamp.fr, stable@vger.kernel.org, Yaroslav Dudkov Subject: Re: [PATCH net] tunnels: Drop stale dst when building an ICMP error for PMTUD Date: Wed, 2 Sep 2026 19:50:10 +0000 Message-ID: <20260902195012.265628-1-aroslavdudkov622@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260902190112.4126199-1-idosch@nvidia.com> References: <20260902190112.4126199-1-idosch@nvidia.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Wed, Sep 02, 2026 at 07:01:12PM +0000, Ido Schimmel wrote: > Fix this by making sure that the ICMP error packet does not have a valid > dst entry, thereby forcing the IP layer to perform a route lookup. Tested on net with this patch applied: - pmtu.sh: all 16 bridged and all 16 OVS subtests pass, both with and without br_netfilter loaded. Without the patch, loading br_netfilter makes all 16 bridged subtests fail (the reply gets delivered and exits with the old -w 1 failure). - The forwarded-sender reproducer from my earlier mail goes from 10 tx / 0 rx / no errors to 10 tx / 8 rx / +1 error, the error being "From 192.168.4.1 icmp_seq=1 Frag needed and DF set (mtu = 3950)" -- the tunnel's PTB reaching the sender. Tested-by: Yaroslav Dudkov