Re: kernel panic by enabling net.inet.ip.random_id

From: Shawn Webb <shawn.webb_at_hardenedbsd.org>
Date: Wed, 6 Jan 2016 13:24:53 -0500
That's what gets toggled via the sysctl. I think I figured out that I
need to call ip_initid() in the SYSINIT. Compiling and testing now.

Thanks,

Shawn

On Wed, Jan 06, 2016 at 10:15:08AM -0800, Adrian Chadd wrote:
> Why'd you condition the vimage definition? :)
> 
> 
> 
> -a
> 
> 
> On 6 January 2016 at 06:46, Shawn Webb <shawn.webb_at_hardenedbsd.org> wrote:
> > (kgdb) list *(0xffffffff80b5de9e)
> > 0xffffffff80b5de9e is in ip_fillid (/usr/src/sys/netinet/ip_id.c:237).
> > warning: Source file is more recent than executable.
> >
> > 232             new_id = 0;
> > 233             do {
> > 234                     if (new_id != 0)
> > 235                             V_random_id_collisions++;
> > 236                     arc4rand(&new_id, sizeof(new_id), 0);
> > 237             } while (bit_test(V_id_bits, new_id) || new_id == 0);
> > 238             bit_clear(V_id_bits, V_id_array[V_array_ptr]);
> > 239             bit_set(V_id_bits, new_id);
> > 240             V_id_array[V_array_ptr] = new_id;
> > 241             V_array_ptr++;
> >
> > This is the change I made to ip_id.c that caused the underlying kernel
> > panic:
> > https://github.com/HardenedBSD/hardenedBSD/commit/52d5a93b92097e7a79be8d2e0eb9c1a58b8337d1
> >
> > Ideally, we should be able to just toggle that variable and all would be
> > well. But it seems with the VIMAGE work, something is preventing that.
> >
> > Thanks,
> >
> > Shawn
> >
> > On Tue, Jan 05, 2016 at 06:22:34PM -0800, Adrian Chadd wrote:
> >> try list *(0x[address]) .
> >>
> >> That line is mtx_unlock(), which makes no sense (as mtx_lock succeeded fine.)
> >>
> >>
> >> -a
> >>
> >>
> >> On 5 January 2016 at 18:13, Shawn Webb <shawn.webb_at_hardenedbsd.org> wrote:
> >> > Thanks for the quick reply! Here's some more debugging output:
> >> >
> >> > === Begin Log ===
> >> > (kgdb) bt
> >> > #0  doadump (textdump=0) at pcpu.h:221
> >> > #1  0xffffffff8037c78b in db_dump (dummy=<value optimized out>, dummy2=false, dummy3=0, dummy4=0x0) at /usr/src/sys/ddb/db_command.c:533
> >> > #2  0xffffffff8037c57e in db_command (cmd_table=0x0) at /usr/src/sys/ddb/db_command.c:440
> >> > #3  0xffffffff8037c314 in db_command_loop () at /usr/src/sys/ddb/db_command.c:493
> >> > #4  0xffffffff8037edab in db_trap (type=<value optimized out>, code=0) at /usr/src/sys/ddb/db_main.c:251
> >> > #5  0xffffffff80a5c563 in kdb_trap (type=12, code=0, tf=<value optimized out>) at /usr/src/sys/kern/subr_kdb.c:654
> >> > #6  0xffffffff80e6b7e1 in trap_fatal (frame=0xfffffe02c33894d0, eva=<value optimized out>) at /usr/src/sys/amd64/amd64/trap.c:829
> >> > #7  0xffffffff80e6ba2d in trap_pfault (frame=0xfffffe02c33894d0, usermode=<value optimized out>) at /usr/src/sys/amd64/amd64/trap.c:684
> >> > #8  0xffffffff80e6b15f in trap (frame=0xfffffe02c33894d0) at /usr/src/sys/amd64/amd64/trap.c:435
> >> > #9  0xffffffff80e4af97 in calltrap () at /usr/src/sys/amd64/amd64/exception.S:234
> >> > #10 0xffffffff80b5de9e in ip_fillid (ip=0xfffff8000ef8cb88) at /usr/src/sys/netinet/ip_id.c:237
> >> > #11 0xffffffff80b6c41b in ip_output (m=<value optimized out>, opt=<value optimized out>, ro=<value optimized out>, flags=0, imo=0x0, inp=0xfffff8000e66e960) at /usr/src/sys/netinet/ip_output.c:268
> >> > #12 0xffffffff80bf0612 in udp_send (so=<value optimized out>, flags=<value optimized out>, m=<value optimized out>, addr=0x0, control=<value optimized out>, td=0xfffff8000ef8cb88) at /usr/src/sys/netinet/udp_usrreq.c:1517
> >> > #13 0xffffffff80aa3872 in sosend_dgram (so=0xfffff8000e6422e8, addr=0x0, uio=<value optimized out>, top=0xfffff8000ef8cb00, control=0x0, flags=<value optimized out>, td=0xffffffff81bef2ec) at /usr/src/sys/kern/uipc_socket.c:1164
> >> > #13 0xffffffff80aa3872 in sosend_dgram (so=0xfffff8000e6422e8, addr=0x0, uio=<value optimized out>, top=0xfffff8000ef8cb00, control=0x0, flags=<value optimized out>, td=0xffffffff81bef2ec) at /usr/src/sys/kern/uipc_socket.c:1164
> >> > #14 0xffffffff80aaa03b in kern_sendit (td=0xfffff8000e4cd9c0, s=6, mp=<value optimized out>, flags=0, control=0x0, segflg=UIO_USERSPACE) at /usr/src/sys/kern/uipc_syscalls.c:906
> >> > #15 0xffffffff80aaa336 in sendit (td=0xfffff8000e4cd9c0, s=<value optimized out>, mp=0xfffffe02c3389970, flags=3980) at /usr/src/sys/kern/uipc_syscalls.c:833
> >> > #16 0xffffffff80aaa1fd in sys_sendto (td=0x0, uap=<value optimized out>) at /usr/src/sys/kern/uipc_syscalls.c:957
> >> > #17 0xffffffff80e6bfdb in amd64_syscall (td=0xfffff8000e4cd9c0, traced=0) at subr_syscall.c:135
> >> > #18 0xffffffff80e4b27b in Xfast_syscall () at /usr/src/sys/amd64/amd64/exception.S:394
> >> > #19 0x000003e339782e8a in ?? ()
> >> > (kgdb) x/i 0xffffffff80b5de9e
> >> > 0xffffffff80b5de9e <ip_fillid+142>:     movzbl (%rax,%rcx,1),%esi
> >> > (kgdb) info reg
> >> > rax            0x0      0
> >> > rbx            0x0      0
> >> > rcx            0x0      0
> >> > rdx            0x0      0
> >> > rsi            0x0      0
> >> > rdi            0x0      0
> >> > rbp            0xfffffe02c3388fe0       0xfffffe02c3388fe0
> >> > rsp            0xfffffe02c3388fc8       0xfffffe02c3388fc8
> >> > r8             0x0      0
> >> > r9             0x0      0
> >> > r10            0x0      0
> >> > r11            0x0      0
> >> > r12            0xffffffff817c0b80       -2122577024
> >> > r13            0xffffffff817c1470       -2122574736
> >> > r14            0x1      1
> >> > r15            0x4      4
> >> > rip            0xffffffff80a1fae3       0xffffffff80a1fae3 <doadump+51>
> >> > eflags         0x0      0
> >> > cs             0x0      0
> >> > ss             0x0      0
> >> > ds             0x0      0
> >> > es             0x0      0
> >> > fs             0x0      0
> >> > gs             0x0      0
> >> > === End Log ===
> >> >
> >> > Thanks,
> >> >
> >> > Shawn
> >> >
> >> > On Tue, Jan 05, 2016 at 06:06:41PM -0800, Adrian Chadd wrote:
> >> >> looks like a null pointer deference. What's kgdb show at that IP?
> >> >>
> >> >>
> >> >> -a
> >> >>
> >> >>
> >> >> On 5 January 2016 at 17:57, Shawn Webb <shawn.webb_at_hardenedbsd.org> wrote:
> >> >> > Hey All,
> >> >> >
> >> >> > Here's a kernel panic I'm experiencing by enabling net.inet.ip.random_id
> >> >> > at boot.
> >> >> >
> >> >> > I'm on latest HEAD on amd64 in bhyve. I'll soon-ish be testing on native
> >> >> > hardware with VIMAGE enabled.
> >> >> >
> >> >> > === Begin Log ===
> >> >> > Kernel page fault with the following non-sleepable locks held:
> >> >> > exclusive sleep mutex ip_id_mtx (ip_id_mtx) r = 0 (0xffffffff81c54830) locked _at_ /usr/src/sys/netinet/ip_id.c:227
> >> >> > stack backtrace:
> >> >> > #0 0xffffffff80a79620 at witness_debugger+0x70
> >> >> > #1 0xffffffff80a7a937 at witness_warn+0x3d7
> >> >> > #2 0xffffffff80e6b887 at trap_pfault+0x57
> >> >> > #3 0xffffffff80e6b15f at trap+0x4bf
> >> >> > #4 0xffffffff80e4af97 at calltrap+0x8
> >> >> > #5 0xffffffff80b6c41b at ip_output+0x16b
> >> >> > #6 0xffffffff80b68e82 at icmp_reflect+0x5b2
> >> >> > #7 0xffffffff80b6883f at icmp_error+0x46f
> >> >> > #8 0xffffffff80beeb12 at udp_input+0x982
> >> >> > #9 0xffffffff80b69d1d at ip_input+0x17d
> >> >> > #10 0xffffffff80b08ba1 at netisr_dispatch_src+0x81
> >> >> > #11 0xffffffff80afecce at ether_demux+0x15e
> >> >> > #12 0xffffffff80affa14 at ether_nh_input+0x344
> >> >> > #13 0xffffffff80b08ba1 at netisr_dispatch_src+0x81
> >> >> > #14 0xffffffff80afefcf at ether_input+0x4f
> >> >> > #15 0xffffffff8089a5c3 at vtnet_rxq_eof+0x823
> >> >> > #16 0xffffffff8089b2ce at vtnet_rx_vq_intr+0x4e
> >> >> > #17 0xffffffff809e9ba6 at intr_event_execute_handlers+0x96
> >> >> >
> >> >> >
> >> >> > Fatal trap 12: page fault while in kernel mode
> >> >> > cpuid = 6; apic id = 06
> >> >> > fault virtual address   = 0x5bd
> >> >> > fault code              = supervisor read data, page not present
> >> >> > instruction pointer     = 0x20:0xffffffff80b5de9e
> >> >> > stack pointer           = 0x28:0xfffffe02b8d483e0
> >> >> > frame pointer           = 0x28:0xfffffe02b8d48410
> >> >> > code segment            = base 0x0, limit 0xfffff, type 0x1b
> >> >> >                         = DPL 0, pres 1, long 1, def32 0, gran 1
> >> >> > processor eflags        = interrupt enabled, resume, IOPL = 0
> >> >> > current process         = 12 (irq265: virtio_pci0)
> >> >> > [ thread pid 12 tid 100040 ]
> >> >> > Stopped at      ip_fillid+0x8e: movzbl  (%rax,%rcx,1),%esi
> >> >> > === End Log ===
> >> >> >
> >> >> > Thanks,
> >> >> >
> >> >> > --
> >> >> > Shawn Webb
> >> >> > HardenedBSD
> >> >> >
> >> >> > GPG Key ID:          0x6A84658F52456EEE
> >> >> > GPG Key Fingerprint: 2ABA B6BD EF6A F486 BE89  3D9E 6A84 658F 5245 6EEE
> >> >
> >> > --
> >> > Shawn Webb
> >> > HardenedBSD
> >> >
> >> > GPG Key ID:          0x6A84658F52456EEE
> >> > GPG Key Fingerprint: 2ABA B6BD EF6A F486 BE89  3D9E 6A84 658F 5245 6EEE
> >
> > --
> > Shawn Webb
> > HardenedBSD
> >
> > GPG Key ID:          0x6A84658F52456EEE
> > GPG Key Fingerprint: 2ABA B6BD EF6A F486 BE89  3D9E 6A84 658F 5245 6EEE

-- 
Shawn Webb
HardenedBSD

GPG Key ID:          0x6A84658F52456EEE
GPG Key Fingerprint: 2ABA B6BD EF6A F486 BE89  3D9E 6A84 658F 5245 6EEE

Received on Wed Jan 06 2016 - 17:24:59 UTC

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