pf crash + questions

Richard Nyberg rnyberg at murmeldjur.se
Sat Jul 29 09:27:36 PDT 2006


My dragonfy firewall panics now and then. Using bittorrent greatly enhances
the chances of a panic. Unfortunately the backtraces from the core dumps have
mostly looked like garbage.

Today I enabled DDB on panic and I've had two virtually identical crashes.
The kernel is GENERIC from 1.6.0. Below is the fault and trace (typo warning:
it was copied by hand).

I still have the core dumps if they're needed.

--------------------------
Fatal trap 12: page fault while in kernel mode
fault virtual address = 0x383d185e
fault code = supervisor read, page not present
ip = 0x8:0xd53cca40
sp = 0x10:0xd53cca2c
fp = 0x10:0xd53cca50

stopped at 0xd53cca40: idivb 0x6399431e(%eax),%al

db> trace
_end(d53ccc2c, 8716c678, 0, 0) at 0xd53cca40
pf_test_state_tcp(d53ccbf4, 1, d6c46300, d833b200, 14) at pf_test_state_tcp + 0x945
pf_test(1, ccef90b8, d53cccd8, c17048c0, 1) at pf_test + 0x333
pf_check_in(0, d53cccd8, cc3f90b8, 1, d833b200) at pf_check_in + 0x26
pfil_run_hooks(c05f2f20, d53ccd70, ccef90b8, 1, 3040b652) at pfil_run_hooks + 0x59
ip_input(d833b200, d53ccd84, c0357f61, d833b214, 0) at ip_input + 0x2a8
ip_input_handler(d833b214, 0, 0, c02c02220, 0) at ip_input_handler + 0x14
tcpmsg_service_loop(0, 0, 0, 0, 0) at tcpmsg_service_loop + 0xe
lwkt_exit() at lwkt_exit
---------------------------------------

Some questions
1) Is the correct way to generate a core dump from DDB to "call dumpsys"?

2)
The output from "call dumpsys" ended something like this:
. ....8 7 6 5 4 3 2 1 0 error2 0
succeded!
0xa

What does error2 mean?

3) How do I produce the trace above from kgdb? I'd prefer not having to
copy it by hand :)

Happy hacking!
        -Richard






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