bisecting fixing commit since ff33472c282e209da54cbc0c7c1c06ddfcc93d33
building syzkaller on de453f342be9edcca7de5a41e153ced8ad7f1a70
testing commit ff33472c282e209da54cbc0c7c1c06ddfcc93d33 with gcc (GCC) 8.1.0
kernel signature: 7da295987e3852ecc82db7954f29b45344377ee488c63aff7715d22515697c84
run #0: crashed: WARNING: locking bug in do_ipv6_setsockopt
run #1: crashed: KASAN: use-after-free Read in l2tp_session_create
run #2: crashed: WARNING: locking bug in do_ipv6_setsockopt
run #3: crashed: WARNING: locking bug in do_ipv6_setsockopt
run #4: crashed: KASAN: use-after-free Read in lock_sock_nested
run #5: crashed: KASAN: use-after-free Read in l2tp_session_create
run #6: crashed: WARNING: locking bug in do_ipv6_setsockopt
run #7: crashed: WARNING: locking bug in do_ipv6_setsockopt
run #8: crashed: WARNING: locking bug in do_ipv6_setsockopt
run #9: crashed: WARNING: locking bug in do_ipv6_setsockopt
testing current HEAD b850307b279cbd12ab8c654d1a3dfe55319cc475
testing commit b850307b279cbd12ab8c654d1a3dfe55319cc475 with gcc (GCC) 8.1.0
kernel signature: a33f410a1467815d69905329d4236593f3907f77689b4f3580a0606acb80467b
run #0: crashed: general protection fault in pppol2tp_session_init
run #1: crashed: general protection fault in pppol2tp_session_init
run #2: crashed: general protection fault in pppol2tp_session_init
run #3: crashed: general protection fault in pppol2tp_session_init
run #4: crashed: general protection fault in pppol2tp_session_init
run #5: crashed: general protection fault in pppol2tp_session_init
run #6: crashed: general protection fault in pppol2tp_session_init
run #7: crashed: general protection fault in pppol2tp_session_init
run #8: crashed: WARNING: locking bug in do_ipv6_setsockopt
run #9: crashed: general protection fault in pppol2tp_session_init
revisions tested: 2, total time: 24m19.462581399s (build: 15m31.288123787s, test: 8m6.044736521s)
the crash still happens on HEAD
commit msg: Linux 4.14.184
crash: general protection fault in pppol2tp_session_init
l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9
l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 22621 Comm: syz-executor.3 Not tainted 4.14.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88809f7902c0 task.stack: ffff888096a28000
RIP: 0010:__read_once_size include/linux/compiler.h:183 [inline]
RIP: 0010:sk_dst_get include/net/sock.h:1766 [inline]
RIP: 0010:pppol2tp_session_init+0x1c1/0x480 net/l2tp/l2tp_ppp.c:616
RSP: 0018:ffff888096a2fb88 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff8880980df240 RCX: 1ffffffff0eda7ac
RDX: 0000000000000045 RSI: ffffffff86bce1e0 RDI: 0000000000000228
RBP: ffff888096a2fbb0 R08: ffff88809f790b90 R09: 0000000000000000
R10: 0000000000000028 R11: ffff88809f7902c0 R12: 0000000000000000
R13: 000000000000585d R14: ffff888096a2fd28 R15: ffff88808e230e40
FS:  00007ff9b5ee0700(0000) GS:ffff8880aee00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000095259000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 pppol2tp_connect+0xce4/0x1380 net/l2tp/l2tp_ppp.c:790
 SYSC_connect+0x1e3/0x2a0 net/socket.c:1655
 SyS_connect+0x9/0x10 net/socket.c:1636
 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x459829
RSP: 002b:00007ff9b5edfc78 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459829
RDX: 0000000000000026 RSI: 0000000020000180 RDI: 0000000000000007
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff9b5ee06d4
R13: 00000000004bfd8b R14: 00000000004d1948 R15: 00000000ffffffff
Code: 5a 85 c0 74 0d 80 3d ac 7f 9d 02 00 0f 84 0c 02 00 00 49 8d bc 24 28 02 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 8d 02 00 00 4d 8b b4 24 28 02 00 00 e8 88 b1 
RIP: __read_once_size include/linux/compiler.h:183 [inline] RSP: ffff888096a2fb88
RIP: sk_dst_get include/net/sock.h:1766 [inline] RSP: ffff888096a2fb88
RIP: pppol2tp_session_init+0x1c1/0x480 net/l2tp/l2tp_ppp.c:616 RSP: ffff888096a2fb88
---[ end trace 8bfc284280ea61e6 ]---