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[2a01:cb05:8d65:2b00:fa0f:162c:47a2:f35b]) by smtp.gmail.com with ESMTPSA id e21-20020a05600c219500b003f736735424sm9067513wme.43.2023.06.06.07.11.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 06 Jun 2023 07:11:25 -0700 (PDT) Date: Tue, 6 Jun 2023 16:11:24 +0200 From: Guillaume Nault To: Mirsad Todorovac Cc: netdev@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Shuah Khan , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: POSSIBLE BUG: selftests/net/fcnal-test.sh: [FAIL] in vrf "bind - ns-B IPv6 LLA" test Message-ID: References: <60f78eaa-ace7-c27d-8e45-4777ecf3faa2@alu.unizg.hr> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <60f78eaa-ace7-c27d-8e45-4777ecf3faa2@alu.unizg.hr> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 06, 2023 at 03:57:35PM +0200, Mirsad Todorovac wrote: > diff --git a/net/ipv6/ping.c b/net/ipv6/ping.c > index c4835dbdfcff..c1d81c49b775 100644 > --- a/net/ipv6/ping.c > +++ b/net/ipv6/ping.c > @@ -73,6 +73,10 @@ static int ping_v6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) > struct rt6_info *rt; > struct pingfakehdr pfh; > struct ipcm6_cookie ipc6; > + struct net *net = sock_net(sk); > + struct net_device *dev = NULL; > + struct net_device *mdev = NULL; > + struct net_device *bdev = NULL; > > err = ping_common_sendmsg(AF_INET6, msg, len, &user_icmph, > sizeof(user_icmph)); > @@ -111,10 +115,26 @@ static int ping_v6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) > else if (!oif) > oif = np->ucast_oif; > > + if (oif) { > + rcu_read_lock(); > + dev = dev_get_by_index_rcu(net, oif); > + rcu_read_unlock(); You can't assume '*dev' is still valid after rcu_read_unlock() unless you hold a reference on it. > + rtnl_lock(); > + mdev = netdev_master_upper_dev_get(dev); > + rtnl_unlock(); Because of that, 'dev' might have already disappeared at the time netdev_master_upper_dev_get() is called. So it may dereference an invalid pointer here. > + } > + > + if (sk->sk_bound_dev_if) { > + rcu_read_lock(); > + bdev = dev_get_by_index_rcu(net, sk->sk_bound_dev_if); > + rcu_read_unlock(); > + } > + > addr_type = ipv6_addr_type(daddr); > if ((__ipv6_addr_needs_scope_id(addr_type) && !oif) || > (addr_type & IPV6_ADDR_MAPPED) || > - (oif && sk->sk_bound_dev_if && oif != sk->sk_bound_dev_if)) > + (oif && sk->sk_bound_dev_if && oif != sk->sk_bound_dev_if && > + !(mdev && sk->sk_bound_dev_if && bdev && mdev == bdev))) > return -EINVAL; > > ipcm6_init_sk(&ipc6, np); > > However, this works by the test (888 passed) but your two liner is obviously > better :-) :) > Best regards, > Mirsad > > -- > Mirsad Goran Todorovac > Sistem inženjer > Grafički fakultet | Akademija likovnih umjetnosti > Sveučilište u Zagrebu > > System engineer > Faculty of Graphic Arts | Academy of Fine Arts > University of Zagreb, Republic of Croatia >