Messages in this thread | | | From | Kuniyuki Iwashima <> | Subject | Re: kernel BUG in fou_build_udp | Date | Mon, 17 Apr 2023 08:26:59 -0700 |
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From: Eric Dumazet <edumazet@google.com> Date: Mon, 17 Apr 2023 11:00:20 +0200 > On Sat, Apr 15, 2023 at 9:44 PM Kuniyuki Iwashima <kuniyu@amazon.com> wrote: > > > > Hi, > > > > Thanks for reporting the issue. > > > > From: Palash Oswal <oswalpalash@gmail.com> > > Date: Thu, 13 Apr 2023 20:35:52 -0700 > > > Hello, > > > I found the following issue using syzkaller with enriched corpus on: > > > HEAD commit : 0bcc4025550403ae28d2984bddacafbca0a2f112 > > > git tree: linux > > > > > > C Reproducer : https://gist.github.com/oswalpalash/2a4bdb639c605ec80dbeec220e09603c > > > Kernel .config : > > > https://gist.github.com/oswalpalash/d9580b0bfce202b37445fa5fd426e41f > > > syz-repro : > > > r0 = socket$inet6(0xa, 0x2, 0x0) > > > r1 = socket$nl_route(0x10, 0x3, 0x0) > > > r2 = socket(0x10, 0x803, 0x0) > > > sendmsg$nl_route(r2, &(0x7f0000000380)={0x0, 0x0, > > > &(0x7f0000000340)={0x0, 0x14}}, 0x0) > > > getsockname$packet(r2, &(0x7f0000000100)={0x11, 0x0, <r3=>0x0, 0x1, > > > 0x0, 0x6, @broadcast}, &(0x7f00000000c0)=0x14) > > > sendmsg$nl_route(r1, &(0x7f0000000080)={0x0, 0x0, > > > &(0x7f0000000500)={&(0x7f0000000180)=@newlink={0x60, 0x10, 0x439, 0x0, > > > 0x0, {0x0, 0x0, 0x0, 0x0, 0x9801}, [@IFLA_LINKINFO={0x40, 0x12, 0x0, > > > 0x1, @sit={{0x8}, {0x34, 0x2, 0x0, 0x1, [@IFLA_IPTUN_LINK={0x8, 0x1, > > > r3}, @IFLA_IPTUN_ENCAP_TYPE={0x6, 0xf, 0x2}, > > > @IFLA_IPTUN_ENCAP_SPORT={0x6, 0x11, 0x4e21}, > > > @IFLA_IPTUN_ENCAP_SPORT={0x6, 0x11, 0x4e24}, @IFLA_IPTUN_LOCAL={0x8, > > > 0x2, @dev={0xac, 0x14, 0x14, 0x16}}, @IFLA_IPTUN_ENCAP_FLAGS={0x6, > > > 0x10, 0xfff}]}}}]}, 0x60}}, 0x20048894) > > > sendmmsg$inet(r0, &(0x7f00000017c0)=[{{&(0x7f0000000040)={0x2, 0x4e20, > > > @multicast1}, 0x10, 0x0, 0x0, &(0x7f0000000000)=[@ip_pktinfo={{0x1c, > > > 0x0, 0x8, {r3, @empty, @remote}}}], 0x20}}], 0x1, 0x0) > > > > > > > > > Console log: > > > > > > skbuff: skb_under_panic: text:ffffffff88a09da0 len:48 put:8 > > > head:ffff88801e4be680 data:ffff88801e4be67c tail:0x2c end:0x140 > > > dev:sit1 > > > ------------[ cut here ]------------ > > > kernel BUG at net/core/skbuff.c:150! > > > invalid opcode: 0000 [#1] PREEMPT SMP KASAN > > > CPU: 0 PID: 10068 Comm: syz-executor.3 Not tainted > > > 6.3.0-rc6-pasta-00035-g0bcc40255504 #1 > > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS > > > 1.13.0-1ubuntu1.1 04/01/2014 > > > RIP: 0010:skb_panic+0x152/0x1d0 > > > Code: 0f b6 04 01 84 c0 74 04 3c 03 7e 20 8b 4b 70 41 56 45 89 e8 48 > > > c7 c7 80 b3 5b 8b 41 57 56 48 89 ee 52 4c 89 e2 e8 ae 15 6c f9 <0f> 0b > > > 4c 89 4c 24 10 48 89 54 24 08 48 89 34 24 e8 69 1f d8 f9 4c > > > RSP: 0018:ffffc900029bead0 EFLAGS: 00010282 > > > RAX: 0000000000000084 RBX: ffff88801d1c3d00 RCX: ffffc9000d863000 > > > RDX: 0000000000000000 RSI: ffffffff816695cc RDI: 0000000000000005 > > > RBP: ffffffff8b5bc1e0 R08: 0000000000000005 R09: 0000000000000000 > > > R10: 0000000000000400 R11: 0000000000000000 R12: ffffffff88a09da0 > > > R13: 0000000000000008 R14: ffff8880306b8000 R15: 0000000000000140 > > > FS: 00007f1dae5ed700(0000) GS:ffff888063a00000(0000) knlGS:0000000000000000 > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > CR2: 0000564f403b7d10 CR3: 0000000117f1c000 CR4: 00000000000006f0 > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > Call Trace: > > > <TASK> > > > skb_push+0xc8/0xe0 > > > fou_build_udp+0x30/0x370 > > > > It seems we need skb_cow_head() before skb_push(). > > I'll take a deeper look on the repro. > > Not sure about that. > > The issue looks to be a lack of dev->needed_headroom update as we do > in other tunnels.
I'll check around it as well. Thank you!
> > > > > ---8<--- > > diff --git a/net/ipv4/fou_core.c b/net/ipv4/fou_core.c > > index cafec9b4eee0..24c751f1dbc4 100644 > > --- a/net/ipv4/fou_core.c > > +++ b/net/ipv4/fou_core.c > > @@ -1013,10 +1013,15 @@ EXPORT_SYMBOL(__gue_build_header); > > > > #ifdef CONFIG_NET_FOU_IP_TUNNELS > > > > -static void fou_build_udp(struct sk_buff *skb, struct ip_tunnel_encap *e, > > - struct flowi4 *fl4, u8 *protocol, __be16 sport) > > +static int fou_build_udp(struct sk_buff *skb, struct ip_tunnel_encap *e, > > + struct flowi4 *fl4, u8 *protocol, __be16 sport) > > { > > struct udphdr *uh; > > + int err; > > + > > + err = skb_cow_head(skb, sizeof(*uh)); > > + if (err) > > + return err; > > > > skb_push(skb, sizeof(struct udphdr)); > > skb_reset_transport_header(skb); > > @@ -1030,6 +1035,8 @@ static void fou_build_udp(struct sk_buff *skb, struct ip_tunnel_encap *e, > > fl4->saddr, fl4->daddr, skb->len); > > > > *protocol = IPPROTO_UDP; > > + > > + return 0; > > } > > > > static int fou_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e, > > @@ -1044,9 +1051,7 @@ static int fou_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e, > > if (err) > > return err; > > > > - fou_build_udp(skb, e, fl4, protocol, sport); > > - > > - return 0; > > + return fou_build_udp(skb, e, fl4, protocol, sport); > > } > > > > static int gue_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e, > > @@ -1061,9 +1066,7 @@ static int gue_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e, > > if (err) > > return err; > > > > - fou_build_udp(skb, e, fl4, protocol, sport); > > - > > - return 0; > > + return fou_build_udp(skb, e, fl4, protocol, sport); > > } > > > > static int gue_err_proto_handler(int proto, struct sk_buff *skb, u32 info) > > ---8<--- > > > > Thanks, > > Kuniyuki > > > > > > > gue_build_header+0xfb/0x150 > > > ip_tunnel_xmit+0x66e/0x3150 > > > sit_tunnel_xmit__.isra.0+0xe7/0x150 > > > sit_tunnel_xmit+0xf7e/0x28e0 > > > dev_hard_start_xmit+0x187/0x700 > > > __dev_queue_xmit+0x2ce4/0x3c40 > > > neigh_connected_output+0x3c2/0x550 > > > ip_finish_output2+0x78a/0x22e0 > > > __ip_finish_output+0x396/0x650 > > > ip_finish_output+0x31/0x280 > > > ip_mc_output+0x21f/0x710 > > > ip_send_skb+0xd8/0x260 > > > udp_send_skb+0x73a/0x1480 > > > udp_sendmsg+0x1bb2/0x2840 > > > udpv6_sendmsg+0x1710/0x2c20 > > > inet6_sendmsg+0x9d/0xe0 > > > sock_sendmsg+0xde/0x190 > > > ____sys_sendmsg+0x334/0x900 > > > ___sys_sendmsg+0x110/0x1b0 > > > __sys_sendmmsg+0x18f/0x460 > > > __x64_sys_sendmmsg+0x9d/0x100 > > > do_syscall_64+0x39/0xb0 > > > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > > RIP: 0033:0x7f1dad88eacd > > > Code: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 48 89 f8 48 > > > 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d > > > 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 > > > RSP: 002b:00007f1dae5ecbf8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 > > > RAX: ffffffffffffffda RBX: 00007f1dad9bbf80 RCX: 00007f1dad88eacd > > > RDX: 0000000000000001 RSI: 00000000200017c0 RDI: 0000000000000003 > > > RBP: 00007f1dad8fcb05 R08: 0000000000000000 R09: 0000000000000000 > > > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > > > R13: 00007fff4922802f R14: 00007fff492281d0 R15: 00007f1dae5ecd80 > > > </TASK> > > > Modules linked in: > > > ---[ end trace 0000000000000000 ]--- > > > RIP: 0010:skb_panic+0x152/0x1d0 > > > Code: 0f b6 04 01 84 c0 74 04 3c 03 7e 20 8b 4b 70 41 56 45 89 e8 48 > > > c7 c7 80 b3 5b 8b 41 57 56 48 89 ee 52 4c 89 e2 e8 ae 15 6c f9 <0f> 0b > > > 4c 89 4c 24 10 48 89 54 24 08 48 89 34 24 e8 69 1f d8 f9 4c > > > RSP: 0018:ffffc900029bead0 EFLAGS: 00010282 > > > RAX: 0000000000000084 RBX: ffff88801d1c3d00 RCX: ffffc9000d863000 > > > RDX: 0000000000000000 RSI: ffffffff816695cc RDI: 0000000000000005 > > > RBP: ffffffff8b5bc1e0 R08: 0000000000000005 R09: 0000000000000000 > > > R10: 0000000000000400 R11: 0000000000000000 R12: ffffffff88a09da0 > > > R13: 0000000000000008 R14: ffff8880306b8000 R15: 0000000000000140 > > > FS: 00007f1dae5ed700(0000) GS:ffff888063a00000(0000) knlGS:0000000000000000 > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > CR2: 0000564f403b7d10 CR3: 0000000117f1c000 CR4: 00000000000006f0 > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
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