Re: BUG: unable to handle kernel NULL pointer dereference in cipso_v4_sock_setattr

From: Dmitry Vyukov
Date: Tue Feb 25 2020 - 10:12:25 EST

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On Tue, Feb 25, 2020 at 4:09 PM Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
> > > > > Hello,
> > > > >
> > > > > syzbot found the following crash on:
> > > > >
> > > > > HEAD commit: ca7e1fd1 Merge tag 'linux-kselftest-5.6-rc3' of git://git...
> > > > > git tree: upstream
> > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=179f0931e00000
> > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=a61f2164c515c07f
> > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=f4dfece964792d80b139
> > > > > compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
> > > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14fdfdede00000
> > > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17667de9e00000
> > > > >
> > > > > The bug was bisected to:
> > > > >
> > > > > commit 2303f994b3e187091fd08148066688b08f837efc
> > > > > Author: Peter Krystad <peter.krystad@xxxxxxxxxxxxxxx>
> > > > > Date: Wed Jan 22 00:56:17 2020 +0000
> > > > >
> > > > > mptcp: Associate MPTCP context with TCP socket
> > > > >
> > > > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=14fbec81e00000
> > > > > final crash: https://syzkaller.appspot.com/x/report.txt?x=16fbec81e00000
> > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=12fbec81e00000
> > > > >
> > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > > > > Reported-by: syzbot+f4dfece964792d80b139@xxxxxxxxxxxxxxxxxxxxxxxxx
> > > > > Fixes: 2303f994b3e1 ("mptcp: Associate MPTCP context with TCP socket")
> > > > >
> > > > > BUG: kernel NULL pointer dereference, address: 0000000000000000
> > > > > #PF: supervisor instruction fetch in kernel mode
> > > > > #PF: error_code(0x0010) - not-present page
> > > > > PGD 8e171067 P4D 8e171067 PUD 93fa2067 PMD 0
> > > > > Oops: 0010 [#1] PREEMPT SMP KASAN
> > > > > CPU: 0 PID: 8984 Comm: syz-executor066 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:ffffc900020b7b80 EFLAGS: 00010246
> > > > > RAX: 1ffff110124ba600 RBX: 0000000000000000 RCX: ffff88809fefa600
> > > > > RDX: ffff8880994cdb18 RSI: 0000000000000000 RDI: ffff8880925d3140
> > > > > RBP: ffffc900020b7bd8 R08: ffffffff870225be R09: fffffbfff140652a
> > > > > R10: fffffbfff140652a R11: 0000000000000000 R12: ffff8880925d35d0
> > > > > R13: ffff8880925d3140 R14: dffffc0000000000 R15: 1ffff110124ba6ba
> > > > > FS: 0000000001a0b880(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000
> > > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > > > > CR2: ffffffffffffffd6 CR3: 00000000a6d6f000 CR4: 00000000001406f0
> > > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > > > > Call Trace:
> > > > > cipso_v4_sock_setattr+0x34b/0x470 net/ipv4/cipso_ipv4.c:1888
> > > > > netlbl_sock_setattr+0x2a7/0x310 net/netlabel/netlabel_kapi.c:989
> > > > > smack_netlabel security/smack/smack_lsm.c:2425 [inline]
> > > > > smack_inode_setsecurity+0x3da/0x4a0 security/smack/smack_lsm.c:2716
> > > > > security_inode_setsecurity+0xb2/0x140 security/security.c:1364
> > > > > __vfs_setxattr_noperm+0x16f/0x3e0 fs/xattr.c:197
> > > > > vfs_setxattr fs/xattr.c:224 [inline]
> > > > > setxattr+0x335/0x430 fs/xattr.c:451
> > > > > __do_sys_fsetxattr fs/xattr.c:506 [inline]
> > > > > __se_sys_fsetxattr+0x130/0x1b0 fs/xattr.c:495
> > > > > __x64_sys_fsetxattr+0xbf/0xd0 fs/xattr.c:495
> > > > > do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
> > > > > entry_SYSCALL_64_after_hwframe+0x49/0xbe
> > > >
> > > > Netdev folks, I'm not very familiar with the multipath TCP code so I
> > > > was wondering if you might help me out a bit with this report. Based
> > > > on the stack trace above it looks like for a given AF_INET sock "sk",
> > > > inet_sk(sk)->is_icsk is true but inet_csk(sk) is NULL; should this be
> > > > possible under normal conditions or is there an issue somewhere?
> > >
> > > Paolo has submitted some patch for testing for this bug, not sure if
> > > you have seen it, just in case:
> > > https://groups.google.com/forum/#!msg/syzkaller-bugs/dqwnTBh-MQw/LhgSZYGsBgAJ
> >
> > I sent the patch to the syzbot ML only, for testing before posting on
> > netdev, so Paul likely have not seen it yet, sorry.
> >
> > @Dmitry: I did not get any reply yet from syzbot, are there any
> > problems or is this the usual time-frame?
>
> The testing is queued after bisection of this guy:
> https://syzkaller.appspot.com/bug?id=c0a75a31c5fa84e6e5d3131fd98a5b56e2141b9a
> which has been running since 6pm yesterday...

It's stuck in this boot-broken region. And git bisect degrades to
linear behavior on skipped commits (why?).
If only kernel would have proper presubmit testing to avoid at least
boot breakages... :)

[ 6.784292][ T24] kasan: GPF could be caused by NULL-ptr deref or
user memory access
[ 6.787429][ T24] general protection fault: 0000 [#1] PREEMPT SMP KASAN
[ 6.789312][ T24] CPU: 1 PID: 24 Comm: kworker/u4:2 Not tainted
5.3.0-rc1-syzkaller #0
[ 6.791623][ T24] Hardware name: Google Google Compute
Engine/Google Compute Engine, BIOS Google 01/01/2011
[ 6.791623][ T24] Workqueue: events_unbound async_run_entry_fn
[ 6.795328][ T24] RIP: 0010:dma_direct_max_mapping_size+0x5d/0x128
[ 6.795328][ T24] Code: df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85
c2 00 00 00 4c 8b a3 38 03 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89
e2 48 c1 ea 03 <80> 3c 02 00 0f 85 aa 00 00 00 48 8d bb 48 03 00 00 4d
8b 2c 24 48
[ 6.795328][ T24] RSP: 0000:ffff8880a9adf728 EFLAGS: 00010246
[ 6.806015][ T24] RAX: dffffc0000000000 RBX: ffff88821962b300
RCX: ffffffff8716d938
[ 6.806015][ T24] RDX: 0000000000000000 RSI: 0000000000000040
RDI: ffff88821962b638
[ 6.806015][ T24] RBP: ffff8880a9adf740 R08: ffffed101443d28d
R09: ffffed101443d28d
[ 6.806015][ T24] R10: ffffed101443d28c R11: ffff8880a21e9467
R12: 0000000000000000
[ 6.806015][ T24] R13: ffff88821962b300 R14: ffff8880a28a6a70
R15: 0000000000000200
[ 6.818295][ T24] FS: 0000000000000000(0000)
GS:ffff8880ae900000(0000) knlGS:0000000000000000
[ 6.818446][ T24] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 6.818446][ T24] CR2: 0000000000000000 CR3: 0000000008a6d000
CR4: 00000000001406e0
[ 6.818446][ T24] DR0: 0000000000000000 DR1: 0000000000000000
DR2: 0000000000000000
[ 6.818446][ T24] DR3: 0000000000000000 DR6: 00000000fffe0ff0
DR7: 0000000000000400
[ 6.829410][ T24] Call Trace:
[ 6.829410][ T24] dma_max_mapping_size+0xa2/0xc0
[ 6.831705][ T24] __scsi_init_queue+0x197/0x4f0
[ 6.831705][ T24] scsi_mq_alloc_queue+0xb7/0x150
[ 6.831705][ T24] scsi_alloc_sdev+0x7b7/0xb80
[ 6.831705][ T24] scsi_probe_and_add_lun+0x86a/0x37c0
[ 6.831705][ T24] ? __kasan_check_read+0x11/0x20
[ 6.839613][ T24] ? scsi_alloc_sdev+0xb80/0xb80
[ 6.839613][ T24] ? mark_lock+0xc3/0x1190
[ 6.839613][ T24] ? mark_held_locks+0xb8/0x130
[ 6.839613][ T24] ? _raw_spin_unlock_irqrestore+0x82/0xd0
[ 6.839613][ T24] ? __pm_runtime_resume+0xb4/0x110
[ 6.839613][ T24] ? lockdep_hardirqs_on+0x424/0x5c0
[ 6.839613][ T24] ? _raw_spin_unlock_irqrestore+0x82/0xd0
[ 6.839613][ T24] ? trace_hardirqs_on+0x28/0x1a0
[ 6.851380][ T1] slram: not enough parameters.
[ 6.839613][ T24] ? _raw_spin_unlock_irqrestore+0x6d/0xd0
[ 6.839613][ T24] ? __pm_runtime_resume+0xb4/0x110
[ 6.839613][ T24] __scsi_scan_target+0x1fd/0xc90
[ 6.839613][ T24] ? scsi_add_device+0x30/0x30
[ 6.839613][ T24] ? mark_held_locks+0xb8/0x130
[ 6.839613][ T24] ? _raw_spin_unlock_irqrestore+0x82/0xd0
[ 6.839613][ T24] ? __pm_runtime_resume+0xb4/0x110
[ 6.839613][ T24] ? lockdep_hardirqs_on+0x424/0x5c0
[ 6.839613][ T24] ? _raw_spin_unlock_irqrestore+0x82/0xd0
[ 6.839613][ T24] ? trace_hardirqs_on+0x28/0x1a0
[ 6.839613][ T24] scsi_scan_channel.part.8+0xd6/0x140
[ 6.857364][ T1] ftl_cs: FTL header not found.
[ 6.854615][ T24] scsi_scan_host_selected+0x20c/0x300
[ 6.865470][ T1] Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
[ 6.854615][ T24] ? scsi_scan_host+0x3c0/0x3c0
[ 6.854615][ T24] do_scsi_scan_host+0x1b3/0x250
[ 6.854615][ T24] ? lock_downgrade+0x900/0x900
[ 6.854615][ T24] ? scsi_scan_host+0x3c0/0x3c0
[ 6.854615][ T24] do_scan_async+0x3c/0x450
[ 6.854615][ T24] ? scsi_scan_host+0x3c0/0x3c0
[ 6.854615][ T24] async_run_entry_fn+0xf9/0x4b0
[ 6.854615][ T24] process_one_work+0x856/0x1630
[ 6.854615][ T24] ? pwq_dec_nr_in_flight+0x2c0/0x2c0
[ 6.854615][ T24] ? lock_acquire+0x194/0x410
[ 6.854615][ T24] worker_thread+0x85/0xb60
[ 6.854615][ T24] ? __kthread_parkme+0x47/0x1a0
[ 6.854615][ T24] kthread+0x331/0x3f0
[ 6.854615][ T24] ? process_one_work+0x1630/0x1630
[ 6.854615][ T24] ? kthread_cancel_delayed_work_sync+0x10/0x10
[ 6.854615][ T24] ret_from_fork+0x24/0x30
[ 6.854615][ T24] Modules linked in:
[ 6.907103][ T24] ---[ end trace 14068796cd600dc6 ]---
[ 6.908603][ T24] RIP: 0010:dma_direct_max_mapping_size+0x5d/0x128
[ 6.909683][ T1] eql: Equalizer2002: Simon Janes (simon@xxxxxxx)
and David S. Miller (davem@xxxxxxxxxx)
[ 6.910361][ T24] Code: df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85
c2 00 00 00 4c 8b a3 38 03 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89
e2 48 c1 ea 03 <80> 3c 02 00 0f 85 aa 00 00 00 48 8d bb 48 03 00 00 4d
8b 2c 24 48
[ 6.918535][ T24] RSP: 0000:ffff8880a9adf728 EFLAGS: 00010246
[ 6.919167][ T1] MACsec IEEE 802.1AE
[ 6.920089][ T24] RAX: dffffc0000000000 RBX: ffff88821962b300
RCX: ffffffff8716d938
[ 6.921513][ T1] tun: Universal TUN/TAP device driver, 1.6
[ 6.923553][ T24] RDX: 0000000000000000 RSI: 0000000000000040
RDI: ffff88821962b638
[ 6.932178][ T24] RBP: ffff8880a9adf740 R08: ffffed101443d28d
R09: ffffed101443d28d
[ 6.946172][ T24] R10: ffffed101443d28c R11: ffff8880a21e9467
R12: 0000000000000000
[ 6.952330][ T24] R13: ffff88821962b300 R14: ffff8880a28a6a70
R15: 0000000000000200
[ 6.956636][ T24] FS: 0000000000000000(0000)
GS:ffff8880ae900000(0000) knlGS:0000000000000000
[ 6.964469][ T24] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 6.968832][ T24] CR2: 0000000000000000 CR3: 0000000008a6d000
CR4: 00000000001406e0
[ 6.971517][ T24] DR0: 0000000000000000 DR1: 0000000000000000
DR2: 0000000000000000
[ 6.977961][ T24] DR3: 0000000000000000 DR6: 00000000fffe0ff0
DR7: 0000000000000400
[ 6.983019][ T24] Kernel panic - not syncing: Fatal exception
[ 6.983346][ T1] vcan: Virtual CAN interface driver
[ 6.987331][ T24] Kernel Offset: disabled
[ 6.988609][ T24] Rebooting in 86400 seconds..

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