Samba kernel panics.

[Mark Johnston]

On Tue, Nov 17, 2020 at 08:19:12PM +0200, Konstantin Belousov wrote:
> On Tue, Nov 17, 2020 at 06:20:31PM +0100, Johan Hendriks wrote:
> > Hello all after updating FreeBSD13 from r367724 to r367755 my samba server
> > craches the server.
> > I did rebuild samba 4.11 but that does not help.
> > 
> > The output on the console is the following.
> > 
> > Fatal trap 12: page fault while in kernel mode
> > cpuid =3; apic id = 06
> > fault virtual address    = 0x803a122b8
> > fault code                   = supervisor read instruction, protection
> > violation
> > instruction pointer      = 0x20:0x803a122b8
> > stack pointer               = 0x28:0xfffffe0127733a50
> > frame pointer              = 0x28:0x803a122b0
> > code segment             = base 0x0, limit 0xfffff, type 0x1b
> >                                    = DPL 0, pres 1, long 1, def32 0, gran 1
> > processor eflags          = 17340 (smbd)
> > trap number                = 12
> > panic: page fault
> > cpuid =3
> > time = 1605632521
> > KDB: stack backtrace:
> > db_trace_self_wrapper() at db_trace_setf_wrapper+0x2b/frame
> > 0xfffffe0127733700
> > vpanic() at vpanic+0x182/frame 0xfffffe0127733750
> > panic() at panic+0x43/frame 0xfffffe01277337b0
> > trap_fatal() at trap_fatal+0x387/frame 0xfffffe0127733810
> > trap_pfault() at trap_pfault+0x4f/frame 0xfffffe0127733870
> > trap() at trap+0x27d/frame 0xfffffe0127733980
> > calltrap() at caltrap+0x8/frame 0xfffffe0127733980
> > --- trap 0xc, rip = 0x803a122b8, rsp = 0xfffffe0127733a50, rbp = 0x803a122b0
> > ---
> > KDB: enter: panic
> > [ thread pid 17340 tid 101772 ]
> > stopped at        kdb_enter+0x37: movq     $0,0x1fa9446(%rip)
> > db>
> 
> This looks like SMEP catching an issue, but it is not clear why.

Probably fixed by r367783?  The bug would have partially overwritten the
stack frame, resulting in a jump to a user address after a return.

> Did you clean rebuild of the kernel ?
> 
> What filesystems types do you use ?
> 
> Can you bisect ?  I would actually suspect not clean rebuild after recent
> changes to kern_event.c.