Hi On 30.11.2016 11:39, Andrey Konovalov wrote: > On Sat, Nov 26, 2016 at 5:23 PM, 'Dmitry Vyukov' via syzkaller > <syzkal...@googlegroups.com> wrote: >> Hello, >> >> I got several GPFs in rt6_get_cookie while running syzkaller: >> >> general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN >> Dumping ftrace buffer: >> (ftrace buffer empty) >> Modules linked in: >> CPU: 2 PID: 10156 Comm: syz-executor Not tainted 4.9.0-rc5+ #54 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 >> task: ffff880016f40480 task.stack: ffff88000fc00000 >> RIP: 0010:[<ffffffff87a209e8>] [< inline >] rt6_get_cookie >> include/net/ip6_fib.h:174 >> RIP: 0010:[<ffffffff87a209e8>] [<ffffffff87a209e8>] >> sctp_v6_get_dst+0x7c8/0x1960 net/sctp/ipv6.c:340 >> RSP: 0018:ffff88000fc07298 EFLAGS: 00010202 >> RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc900029f5000 >> RDX: 0000000000000015 RSI: 0000000000000001 RDI: 00000000000000a8 >> RBP: ffff88000fc07580 R08: 0000000000000000 R09: 0000000000000001 >> R10: 0000000000000000 R11: 0000000000000000 R12: ffff880066cd0068 >> R13: 1ffff10001f80e92 R14: ffff880066cd0040 R15: ffff88005f2d2808 >> FS: 00007f52c41f7700(0000) GS:ffff88006d000000(0000) knlGS:0000000000000000 >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> CR2: 0000000020016000 CR3: 0000000065dd7000 CR4: 00000000000006e0 >> DR0: 0000000000000400 DR1: 0000000000000400 DR2: 0000000000000000 >> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 >> Stack: >> ffffffff87a210f6 ffffffff8701ad45 ffff88006768ec20 ffff88006768ec20 >> 0000000000000000 0000000016f40480 ffff88000fc07450 1ffff1000cd9a017 >> ffff88006768ec00 ffff880066fc0730 ffff880066cd0068 1ffff10001f80e66 >> Call Trace: >> [<ffffffff879a313d>] sctp_transport_route+0xad/0x430 >> net/sctp/transport.c:279 >> [<ffffffff8799b106>] sctp_assoc_add_peer+0x5a6/0x13e0 >> net/sctp/associola.c:641 >> [<ffffffff879e8911>] sctp_sendmsg+0x1921/0x3bc0 net/sctp/socket.c:1864 >> [<ffffffff8701ad45>] inet_sendmsg+0x385/0x590 net/ipv4/af_inet.c:734 >> [< inline >] sock_sendmsg_nosec net/socket.c:621 >> [<ffffffff86a6d54f>] sock_sendmsg+0xcf/0x110 net/socket.c:631 >> [<ffffffff86a6ede0>] SYSC_sendto+0x660/0x810 net/socket.c:1656 >> [<ffffffff86a71dd5>] SyS_sendto+0x45/0x60 net/socket.c:1624 >> [<ffffffff88149dc5>] entry_SYSCALL_64_fastpath+0x23/0xc6 >> Code: 00 00 48 8b 84 24 88 00 00 00 48 8b 58 40 e8 80 76 cc f9 48 8d >> bb a8 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> >> 3c 02 00 0f 85 56 0f 00 00 48 8b 9b a8 00 00 00 45 31 ed 48 >> RIP [< inline >] rt6_get_cookie include/net/ip6_fib.h:174 >> RIP [<ffffffff87a209e8>] sctp_v6_get_dst+0x7c8/0x1960 net/sctp/ipv6.c:340 >> RSP <ffff88000fc07298> >> ---[ end trace b8d1354fa571700d ]--- >> >> >> general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN >> Dumping ftrace buffer: >> (ftrace buffer empty) >> Modules linked in: >> CPU: 3 PID: 22744 Comm: syz-executor Not tainted 4.9.0-rc5+ #54 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 >> task: ffff88006b92a840 task.stack: ffff88006a730000 >> RIP: 0010:[<ffffffff87a209e8>] [< inline >] rt6_get_cookie >> include/net/ip6_fib.h:174 >> RIP: 0010:[<ffffffff87a209e8>] [<ffffffff87a209e8>] >> sctp_v6_get_dst+0x7c8/0x1960 net/sctp/ipv6.c:340 >> RSP: 0018:ffff88006a736b88 EFLAGS: 00010202 >> RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90003c4f000 >> RDX: 0000000000000015 RSI: 0000000000000001 RDI: 00000000000000a8 >> RBP: ffff88006a736e68 R08: 0000000000000000 R09: 0000000000000001 >> R10: 0000000000000000 R11: 0000000000000000 R12: ffff880064cff268 >> R13: 1ffff1000d4e6db0 R14: ffff880064cff240 R15: ffff88006a4b6808 >> FS: 00007f74f4ec9700(0000) GS:ffff88006d100000(0000) knlGS:0000000000000000 >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> CR2: 000000002070effc CR3: 000000003bd2f000 CR4: 00000000000006e0 >> DR0: 0000000000000400 DR1: 0000000000000400 DR2: 0000000000000000 >> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 >> Stack: >> ffffffff87a210f6 ffffffff000bbd2d ffff88006c2cd5a0 ffff88006c2cd5a0 >> 0000000000000000 000000006ccb46c0 ffff88006a736d40 1ffff1000c99fe57 >> ffff88006c2cd500 ffff8800658b1f30 ffff880064cff268 1ffff1000d4e6d84 >> Call Trace: >> [<ffffffff879a313d>] sctp_transport_route+0xad/0x430 >> net/sctp/transport.c:279 >> [<ffffffff8799b106>] sctp_assoc_add_peer+0x5a6/0x13e0 >> net/sctp/associola.c:641 >> [<ffffffff879e4358>] __sctp_connect+0x288/0xc90 net/sctp/socket.c:1178 >> [<ffffffff879e4f0b>] __sctp_setsockopt_connectx+0x1ab/0x200 >> net/sctp/socket.c:1332 >> [< inline >] sctp_getsockopt_connectx3 net/sctp/socket.c:1417 >> [<ffffffff879fd2bd>] sctp_getsockopt+0x36ed/0x6800 net/sctp/socket.c:6474 >> [<ffffffff86a76c0a>] sock_common_getsockopt+0x9a/0xe0 net/core/sock.c:2649 >> [< inline >] SYSC_getsockopt net/socket.c:1788 >> [<ffffffff86a724d7>] SyS_getsockopt+0x257/0x390 net/socket.c:1770 >> [<ffffffff88149dc5>] entry_SYSCALL_64_fastpath+0x23/0xc6 >> Code: 00 00 48 8b 84 24 88 00 00 00 48 8b 58 40 e8 80 76 cc f9 48 8d >> bb a8 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> >> 3c 02 00 0f 85 56 0f 00 00 48 8b 9b a8 00 00 00 45 31 ed 48 >> RIP [< inline >] rt6_get_cookie include/net/ip6_fib.h:174 >> RIP [<ffffffff87a209e8>] sctp_v6_get_dst+0x7c8/0x1960 net/sctp/ipv6.c:340 >> RSP <ffff88006a736b88> >> ---[ end trace f42d1c14cb6d2835 ]--- >> >> This happened on commit a25f0944ba9b1d8a6813fd6f1a86f1bd59ac25a6 (Nov 13). >> >> Unfortunately this is not reproducible. >> >> The line is: >> >> return rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0; >> >> Can it be a data race? rt->rt6i_node != NULL, but the next moment it >> is already NULL? That would explain the crash and non-reproducibility >> (need ThreadSanitizer!). >> >> This always happened when called from sctp code, but I don't know if >> it is relevant or not. It happened only 3 times. > > I'm seeing similar crashes from ipv6 and dccp code, reports below. > > [...]
Thanks for the report. Do you have a thread running that concurrently mutates the routing table? Bye, Hannes
