On 2/25/20 12:15 AM, Eric Dumazet wrote: > > > On 2/25/20 12:08 AM, syzbot wrote: >> Hello, >> >> syzbot found the following crash on: >> >> HEAD commit: 54dedb5b Merge tag 'for-linus-5.6-rc3-tag' of git://git.ke.. >> git tree: upstream >> console output: https://syzkaller.appspot.com/x/log.txt?x=168f7de9e00000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=3e57a6b450fb9883 >> dashboard link: https://syzkaller.appspot.com/bug?extid=1938db17e275e85dc328 >> compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81) >> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1681fe09e00000 >> >> IMPORTANT: if you fix the bug, please add the following tag to the commit: >> Reported-by: syzbot+1938db17e275e85dc328@xxxxxxxxxxxxxxxxxxxxxxxxx >> >> BUG: kernel NULL pointer dereference, address: 0000000000000000 >> #PF: supervisor instruction fetch in kernel mode >> #PF: error_code(0x0010) - not-present page >> PGD a0113067 P4D a0113067 PUD a8771067 PMD 0 >> Oops: 0010 [#1] PREEMPT SMP KASAN >> CPU: 0 PID: 10686 Comm: syz-executor.0 Not tainted 5.6.0-rc2-syzkaller #0 >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 >> RIP: 0010:0x0 >> Code: Bad RIP value. >> RSP: 0018:ffffc9000281fce0 EFLAGS: 00010246 >> RAX: 1ffffffff15f48ac RBX: ffffffff8afa4560 RCX: dffffc0000000000 >> RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8880a69a8f40 >> RBP: ffffc9000281fd10 R08: ffffffff86ed9b0c R09: ffffed1014d351f5 >> R10: ffffed1014d351f5 R11: 0000000000000000 R12: ffff8880920d3098 >> R13: 1ffff1101241a613 R14: ffff8880a69a8f40 R15: 0000000000000000 >> FS: 00007f2ae75db700(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> CR2: ffffffffffffffd6 CR3: 00000000a3b85000 CR4: 00000000001406f0 >> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 >> Call Trace: >> inet_release+0x165/0x1c0 net/ipv4/af_inet.c:427 >> __sock_release net/socket.c:605 [inline] >> sock_close+0xe1/0x260 net/socket.c:1283 >> __fput+0x2e4/0x740 fs/file_table.c:280 >> ____fput+0x15/0x20 fs/file_table.c:313 >> task_work_run+0x176/0x1b0 kernel/task_work.c:113 >> tracehook_notify_resume include/linux/tracehook.h:188 [inline] >> exit_to_usermode_loop arch/x86/entry/common.c:164 [inline] >> prepare_exit_to_usermode+0x480/0x5b0 arch/x86/entry/common.c:195 >> syscall_return_slowpath+0x113/0x4a0 arch/x86/entry/common.c:278 >> do_syscall_64+0x11f/0x1c0 arch/x86/entry/common.c:304 >> entry_SYSCALL_64_after_hwframe+0x49/0xbe >> RIP: 0033:0x45c429 >> Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 >> RSP: 002b:00007f2ae75dac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 >> RAX: 0000000000000000 RBX: 00007f2ae75db6d4 RCX: 000000000045c429 >> RDX: 0000000000000001 RSI: 000000000000011a RDI: 0000000000000004 >> RBP: 000000000076bf20 R08: 0000000000000038 R09: 0000000000000000 >> R10: 0000000020000180 R11: 0000000000000246 R12: 00000000ffffffff >> R13: 0000000000000a9d R14: 00000000004ccfb4 R15: 000000000076bf2c >> Modules linked in: >> CR2: 0000000000000000 >> ---[ end trace 82567b5207e87bae ]--- >> RIP: 0010:0x0 >> Code: Bad RIP value. >> RSP: 0018:ffffc9000281fce0 EFLAGS: 00010246 >> RAX: 1ffffffff15f48ac RBX: ffffffff8afa4560 RCX: dffffc0000000000 >> RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8880a69a8f40 >> RBP: ffffc9000281fd10 R08: ffffffff86ed9b0c R09: ffffed1014d351f5 >> R10: ffffed1014d351f5 R11: 0000000000000000 R12: ffff8880920d3098 >> R13: 1ffff1101241a613 R14: ffff8880a69a8f40 R15: 0000000000000000 >> FS: 00007f2ae75db700(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> CR2: ffffffffffffffd6 CR3: 00000000a3b85000 CR4: 00000000001406f0 >> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 >> >> >> --- >> This bug is generated by a bot. It may contain errors. >> See https://goo.gl/tpsmEJ for more information about syzbot. >> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. >> >> syzbot will keep track of this bug report. See: >> https://goo.gl/tpsmEJ#status for how to communicate with syzbot. >> syzbot can test patches for this bug, for details see: >> https://goo.gl/tpsmEJ#testing-patches >> > > Note to ULP maintainers > > Probably the code for IPV6_ADDRFORM needs some care if a TCP socket got ULP enabled ? > Maybe simply make sure sk->sk_prot is pristine as in : diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c index 79fc012dd2cae44b69057c168037b018775d1f49..a72c5c30bc3a55ca65974c537cd089fa4260a8d0 100644 --- a/net/ipv6/ipv6_sockglue.c +++ b/net/ipv6/ipv6_sockglue.c @@ -183,9 +183,14 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname, retv = -EBUSY; break; } - } else if (sk->sk_protocol != IPPROTO_TCP) + } else if (sk->sk_protocol == IPPROTO_TCP) { + if (sk->sk_prot != &tcpv6_prot) { + retv = -EBUSY; + break; + } + } else { break; - + } if (sk->sk_state != TCP_ESTABLISHED) { retv = -ENOTCONN; break;
