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Tue, 09 Jul 2024 03:23:00 -0700 (PDT) Received: from kashwindayan-virtual-machine.eng.vmware.com ([66.170.99.1]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1fbb6a11757sm12832525ad.35.2024.07.09.03.22.58 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 09 Jul 2024 03:22:59 -0700 (PDT) From: Ashwin Kamat To: linux-kernel@vger.kernel.org Cc: gregkh@linuxfoundation.org, davem@davemloft.net, yoshfuji@linux-ipv6.org, dsahern@kernel.org, kuba@kernel.org, netdev@vger.kernel.org, florian.fainelli@broadcom.com, ajay.kaher@broadcom.com, vasavi.sirnapalli@broadcom.com, tapas.kundu@broadcom.com, ashwin.kamat@broadcom.com, Eric Dumazet , Sasha Levin Subject: [PATCH v5.10 1/2] net/ipv6: annotate data-races around cnf.disable_ipv6 Date: Tue, 9 Jul 2024 15:52:49 +0530 Message-Id: <1720520570-9904-2-git-send-email-ashwin.kamat@broadcom.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1720520570-9904-1-git-send-email-ashwin.kamat@broadcom.com> References: <1720520570-9904-1-git-send-email-ashwin.kamat@broadcom.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Eric Dumazet [Upstream commit d289ab65b89c1d4d88417cb6c03e923f21f95fae] disable_ipv6 is read locklessly, add appropriate READ_ONCE() and WRITE_ONCE() annotations. v2: do not preload net before rtnl_trylock() in addrconf_disable_ipv6() (Jiri) Signed-off-by: Eric Dumazet Reviewed-by: Jiri Pirko Signed-off-by: David S. Miller Stable-dep-of: 4db783d68b9b ("ipv6: prevent NULL dereference in ip6_output(= )") Signed-off-by: Sasha Levin [Ashwin: Regenerated the Patch for v5.10] Signed-off-by: Ashwin Dayanand Kamat --- net/ipv6/addrconf.c | 9 +++++---- net/ipv6/ip6_input.c | 2 +- net/ipv6/ip6_output.c | 2 +- 3 files changed, 7 insertions(+), 6 deletions(-) diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 8a6f4cdd5..ac09d4543 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -4107,7 +4107,7 @@ static void addrconf_dad_work(struct work_struct *w) if (!ipv6_generate_eui64(addr.s6_addr + 8, idev->dev) && ipv6_addr_equal(&ifp->addr, &addr)) { /* DAD failed for link-local based on MAC */ - idev->cnf.disable_ipv6 =3D 1; + WRITE_ONCE(idev->cnf.disable_ipv6, 1); =20 pr_info("%s: IPv6 being disabled!\n", ifp->idev->dev->name); @@ -6220,7 +6220,8 @@ static void addrconf_disable_change(struct net *net, = __s32 newf) idev =3D __in6_dev_get(dev); if (idev) { int changed =3D (!idev->cnf.disable_ipv6) ^ (!newf); - idev->cnf.disable_ipv6 =3D newf; + + WRITE_ONCE(idev->cnf.disable_ipv6, newf); if (changed) dev_disable_change(idev); } @@ -6237,7 +6238,7 @@ static int addrconf_disable_ipv6(struct ctl_table *ta= ble, int *p, int newf) =20 net =3D (struct net *)table->extra2; old =3D *p; - *p =3D newf; + WRITE_ONCE(*p, newf); =20 if (p =3D=3D &net->ipv6.devconf_dflt->disable_ipv6) { rtnl_unlock(); @@ -6245,7 +6246,7 @@ static int addrconf_disable_ipv6(struct ctl_table *ta= ble, int *p, int newf) } =20 if (p =3D=3D &net->ipv6.devconf_all->disable_ipv6) { - net->ipv6.devconf_dflt->disable_ipv6 =3D newf; + WRITE_ONCE(net->ipv6.devconf_dflt->disable_ipv6, newf); addrconf_disable_change(net, newf); } else if ((!newf) ^ (!old)) dev_disable_change((struct inet6_dev *)table->extra1); diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c index 4eb9fbfdc..8cf5b10ee 100644 --- a/net/ipv6/ip6_input.c +++ b/net/ipv6/ip6_input.c @@ -165,7 +165,7 @@ static struct sk_buff *ip6_rcv_core(struct sk_buff *skb= , struct net_device *dev, __IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_IN, skb->len); =20 if ((skb =3D skb_share_check(skb, GFP_ATOMIC)) =3D=3D NULL || - !idev || unlikely(idev->cnf.disable_ipv6)) { + !idev || unlikely(READ_ONCE(idev->cnf.disable_ipv6))) { __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS); goto drop; } diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 4126be15e..2b55bf0d3 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -240,7 +240,7 @@ int ip6_output(struct net *net, struct sock *sk, struct= sk_buff *skb) skb->protocol =3D htons(ETH_P_IPV6); skb->dev =3D dev; =20 - if (unlikely(idev->cnf.disable_ipv6)) { + if (unlikely(READ_ONCE(idev->cnf.disable_ipv6))) { IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS); kfree_skb(skb); return 0; --=20 2.45.1 From nobody Sat Feb 7 05:44:14 2026 Received: from mail-pl1-f196.google.com (mail-pl1-f196.google.com [209.85.214.196]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B6270156997 for ; 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charset="utf-8" From: Eric Dumazet [Upstream commit 4db783d68b9b39a411a96096c10828ff5dfada7a] According to syzbot, there is a chance that ip6_dst_idev() returns NULL in ip6_output(). Most places in IPv6 stack deal with a NULL idev just fine, but not here. syzbot reported: general protection fault, probably for non-canonical address 0xdffffc000000= 00bc: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x00000000000005e0-0x00000000000005e7] CPU: 0 PID: 9775 Comm: syz-executor.4 Not tainted 6.9.0-rc5-syzkaller-00157= -g6a30653b604a #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Goo= gle 03/27/2024 RIP: 0010:ip6_output+0x231/0x3f0 net/ipv6/ip6_output.c:237 Code: 3c 1e 00 49 89 df 74 08 4c 89 ef e8 19 58 db f7 48 8b 44 24 20 49 89 = 45 00 49 89 c5 48 8d 9d e0 05 00 00 48 89 d8 48 c1 e8 03 <42> 0f b6 04 38 8= 4 c0 4c 8b 74 24 28 0f 85 61 01 00 00 8b 1b 31 ff = RSP: 0018:ffffc9000927f0d8 EFLAGS: 00010202 RAX: 00000000000000bc RBX: 00000000000005e0 RCX: 0000000000040000 RDX: ffffc900131f9000 RSI: 0000000000004f47 RDI: 0000000000004f48 RBP: 0000000000000000 R08: ffffffff8a1f0b9a R09: 1ffffffff1f51fad R10: dffffc0000000000 R11: fffffbfff1f51fae R12: ffff8880293ec8c0 R13: ffff88805d7fc000 R14: 1ffff1100527d91a R15: dffffc0000000000 FS: 00007f135c6856c0(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020000080 CR3: 0000000064096000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: NF_HOOK include/linux/netfilter.h:314 [inline] ip6_xmit+0xefe/0x17f0 net/ipv6/ip6_output.c:358 sctp_v6_xmit+0x9f2/0x13f0 net/sctp/ipv6.c:248 sctp_packet_transmit+0x26ad/0x2ca0 net/sctp/output.c:653 sctp_packet_singleton+0x22c/0x320 net/sctp/outqueue.c:783 sctp_outq_flush_ctrl net/sctp/outqueue.c:914 [inline] sctp_outq_flush+0x6d5/0x3e20 net/sctp/outqueue.c:1212 sctp_side_effects net/sctp/sm_sideeffect.c:1198 [inline] sctp_do_sm+0x59cc/0x60c0 net/sctp/sm_sideeffect.c:1169 sctp_primitive_ASSOCIATE+0x95/0xc0 net/sctp/primitive.c:73 __sctp_connect+0x9cd/0xe30 net/sctp/socket.c:1234 sctp_connect net/sctp/socket.c:4819 [inline] sctp_inet_connect+0x149/0x1f0 net/sctp/socket.c:4834 __sys_connect_file net/socket.c:2048 [inline] __sys_connect+0x2df/0x310 net/socket.c:2065 __do_sys_connect net/socket.c:2075 [inline] __se_sys_connect net/socket.c:2072 [inline] __x64_sys_connect+0x7a/0x90 net/socket.c:2072 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f Fixes: 778d80be5269 ("ipv6: Add disable_ipv6 sysctl to disable IPv6 operaio= n on specific interface.") Reported-by: syzbot Signed-off-by: Eric Dumazet Reviewed-by: Larysa Zaremba Link: https://lore.kernel.org/r/20240507161842.773961-1-edumazet@google.com Signed-off-by: Jakub Kicinski [Ashwin: Regenerated the Patch for v5.10] Signed-off-by: Ashwin Dayanand Kamat --- net/ipv6/ip6_output.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 2b55bf0d3..32512b8ca 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -240,7 +240,7 @@ int ip6_output(struct net *net, struct sock *sk, struct= sk_buff *skb) skb->protocol =3D htons(ETH_P_IPV6); skb->dev =3D dev; =20 - if (unlikely(READ_ONCE(idev->cnf.disable_ipv6))) { + if (unlikely(!idev || READ_ONCE(idev->cnf.disable_ipv6))) { IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS); kfree_skb(skb); return 0; --=20 2.45.1