| Message ID | 20240709010247.84658-2-vinicius.peixoto@canonical.com |
|---|---|
| State | New |
| Headers | show |
| Series | CVE-2024-36901 | expand |
On 09-07-2024 03:02, Vinicius Peixoto wrote: > From: Eric Dumazet <edumazet@google.com> > > 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 0xdffffc00000000bc: 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 Google 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 84 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: > <TASK> > 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 operaion on specific interface.") > Reported-by: syzbot <syzkaller@googlegroups.com> > Signed-off-by: Eric Dumazet <edumazet@google.com> > Reviewed-by: Larysa Zaremba <larysa.zaremba@intel.com> > Link: https://lore.kernel.org/r/20240507161842.773961-1-edumazet@google.com > Signed-off-by: Jakub Kicinski <kuba@kernel.org> > > CVE-2024-36901 > (backported from commit 4db783d68b9b39a411a96096c10828ff5dfada7a) > [vpeixoto: upstream commit 5e187189ec32 ("net: ip: add skb drop reasons > for ip egress path)" does not exist in this kernel and makes a superfluous > change that introduces a context conflict at the `kfree_skb` call.] > Signed-off-by: Vinicius Peixoto <vinicius.peixoto@canonical.com> > --- > 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 3b1efab423b8b..e72b47bf8af97 100644 > --- a/net/ipv6/ip6_output.c > +++ b/net/ipv6/ip6_output.c > @@ -221,7 +221,7 @@ int ip6_output(struct net *net, struct sock *sk, struct sk_buff *skb) > skb->protocol = htons(ETH_P_IPV6); > skb->dev = dev; > > - if (unlikely(idev->cnf.disable_ipv6)) { READ_ONCE was introduced in d289ab65b89c1d: `ipv6: annotate data-races around cnf.disable_ipv6` along with other access to idev->cnf.disable_ipv6. It's best to not introduce it here. > + if (unlikely(!idev || READ_ONCE(idev->cnf.disable_ipv6))) { > IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS); > kfree_skb(skb); > return 0;
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 3b1efab423b8b..e72b47bf8af97 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -221,7 +221,7 @@ int ip6_output(struct net *net, struct sock *sk, struct sk_buff *skb) skb->protocol = htons(ETH_P_IPV6); skb->dev = dev; - if (unlikely(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;