Date: Sat, 31 Oct 2015 16:34:43 +0300 From: Alexander V. Chernikov <melifaro@freebsd.org> To: Adrian Chadd <adrian@freebsd.org>, freebsd-current <freebsd-current@freebsd.org>, FreeBSD Net <freebsd-net@freebsd.org> Subject: Re: panic in arptimer in r289937 Message-ID: <2739461446298483@web2h.yandex.ru> In-Reply-To: <CAJ-VmonvVyTNuYv_as41yPCFdfR5T3FE45DP9MKAc-eyzXzPUg@mail.gmail.com> References: null <CAJ-VmonvVyTNuYv_as41yPCFdfR5T3FE45DP9MKAc-eyzXzPUg@mail.gmail.com>
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31.10.2015, 05:32, "Adrian Chadd" <adrian@freebsd.org>:
> Hiya,
>
> Here's a panic from arptimer:
Hi Adrian,
As far as I see, line 205 in if_ether.c is IF_AFDATA_LOCK(ifp) which happens after LLE_WUNLOCK().
So, it looks like (pre-cached) ifp had been freed before locking ifdata.
Do you have any more details on that? (e.g. was some interface detached at that moment, is it reproducible, etc..)
>From a quick glance, potential use-after-free has been possible for quite a long time, but I wonder why it hasn't been observed before.
Probably lltable_free() changes might have triggered that.
I'll take a deeper look on that and reply.
>
> (kgdb) bt
> #0 doadump (textdump=0) at pcpu.h:221
> #1 0xffffffff803666b6 in db_fncall (dummy1=<value optimized out>,
> dummy2=<value optimized out>, dummy3=<value optimized out>,
> dummy4=<value optimized out>) at
> /usr/home/adrian/work/freebsd/head/src/sys/ddb/db_command.c:568
> #2 0xffffffff8036614e in db_command (cmd_table=0x0) at
> /usr/home/adrian/work/freebsd/head/src/sys/ddb/db_command.c:440
> #3 0xffffffff80365ee4 in db_command_loop () at
> /usr/home/adrian/work/freebsd/head/src/sys/ddb/db_command.c:493
> #4 0xffffffff8036897b in db_trap (type=<value optimized out>, code=0)
> at /usr/home/adrian/work/freebsd/head/src/sys/ddb/db_main.c:251
> #5 0xffffffff8096c0f3 in kdb_trap (type=9, code=0, tf=<value
> optimized out>) at
> /usr/home/adrian/work/freebsd/head/src/sys/kern/subr_kdb.c:654
> #6 0xffffffff80d34c81 in trap_fatal (frame=0xfffffe022815d7a0,
> eva=<value optimized out>) at
> /usr/home/adrian/work/freebsd/head/src/sys/amd64/amd64/trap.c:829
> #7 0xffffffff80d34951 in trap (frame=<value optimized out>) at
> /usr/home/adrian/work/freebsd/head/src/sys/amd64/amd64/trap.c:203
> #8 0xffffffff80d149f7 in calltrap () at
> /usr/home/adrian/work/freebsd/head/src/sys/amd64/amd64/exception.S:234
> #9 0xffffffff8092c3fb in _rw_wlock_cookie (c=0xdeadc0dedeadc2de,
> file=0xffffffff81211b1f
> "/usr/home/adrian/work/freebsd/head/src/sys/netinet/if_ether.c",
> line=205)
> at /usr/home/adrian/work/freebsd/head/src/sys/kern/kern_rwlock.c:261
> #10 0xffffffff80a2487f in arptimer (arg=0xfffff8005ecc4000) at
> /usr/home/adrian/work/freebsd/head/src/sys/netinet/if_ether.c:205
> #11 0xffffffff80944c24 in softclock_call_cc (c=0xfffff8005ecc40a8,
> cc=0xffffffff81b2d480, direct=0) at
> /usr/home/adrian/work/freebsd/head/src/sys/kern/kern_timeout.c:722
> #12 0xffffffff80944f87 in softclock (arg=<value optimized out>) at
> /usr/home/adrian/work/freebsd/head/src/sys/kern/kern_timeout.c:851
> #13 0xffffffff808f7eb6 in intr_event_execute_handlers (p=<value
> optimized out>, ie=0xfffff800035a6600) at
> /usr/home/adrian/work/freebsd/head/src/sys/kern/kern_intr.c:1262
> #14 0xffffffff808f8546 in ithread_loop (arg=0xfffff800032c47c0) at
> /usr/home/adrian/work/freebsd/head/src/sys/kern/kern_intr.c:1275
> #15 0xffffffff808f57a4 in fork_exit (callout=0xffffffff808f84a0
> <ithread_loop>, arg=0xfffff800032c47c0, frame=0xfffffe022815dac0) at
> /usr/home/adrian/work/freebsd/head/src/sys/kern/kern_fork.c:1011
> #16 0xffffffff80d14f2e in fork_trampoline () at
> /usr/home/adrian/work/freebsd/head/src/sys/amd64/amd64/exception.S:609
> #17 0x0000000000000000 in ?? ()
> Current language: auto; currently minimal
>
> (kgdb) print *(struct llentry *)c_arg
> $2 = {lle_next = {le_next = 0x0, le_prev = 0xfffff8005e867dc8},
> r_l3addr = {addr4 = {s_addr = 16782508}, addr6 = {__u6_addr =
> {__u6_addr8 = 0xfffff8005ecc4010 "�\024", __u6_addr16 =
> 0xfffff8005ecc4010,
> __u6_addr32 = 0xfffff8005ecc4010}}}, ll_addr = {mac_aligned =
> 110869256150596, mac16 = 0xfffff8005ecc4020, mac8 = 0xfffff8005ecc4020
> "D\036���d"}, spare0 = 0, spare1 = 0, lle_tbl = 0xfffff8005e867e00,
> lle_head = 0xfffff8005e867dc8, lle_free = 0xffffffff80a2c5d0
> <in_lltable_destroy_lle>, la_hold = 0x0, la_numheld = 0, la_expire =
> 2110, la_flags = 1, la_asked = 0, la_preempt = 5, ln_state = 0,
> ln_router = 0, ln_ntick = 0,
> lle_refcnt = 1, lle_chain = {le_next = 0x0, le_prev = 0x0},
> lle_timer = {c_links = {le = {le_next = 0x0, le_prev =
> 0xffffffff81b2d588}, sle = {sle_next = 0x0}, tqe = {tqe_next = 0x0,
> tqe_prev = 0xffffffff81b2d588}},
> c_time = 9066299815445, c_precision = 322122525000, c_arg =
> 0xfffff8005ecc4000, c_func = 0xffffffff80a246e0 <arptimer>, c_lock =
> 0x0, c_flags = 0, c_iflags = 144, c_cpu = 0}, lle_lock = {lock_object
> = {
> lo_name = 0xffffffff8120fbce "lle", lo_flags = 90374144, lo_data
> = 0, lo_witness = 0xfffffe0000b53c80}, rw_lock = 1}}
>
> ..
>
> (kgdb) print *((struct llentry *)c_arg)->lle_tbl
> $4 = {llt_link = {sle_next = 0xdeadc0dedeadc0de}, llt_af = -559038242,
> llt_hsize = -559038242, lle_head = 0xdeadc0dedeadc0de, llt_ifp =
> 0xdeadc0dedeadc0de, llt_lookup = 0xdeadc0dedeadc0de,
> llt_alloc_entry = 0xdeadc0dedeadc0de, llt_delete_entry =
> 0xdeadc0dedeadc0de, llt_prefix_free = 0xdeadc0dedeadc0de,
> llt_dump_entry = 0xdeadc0dedeadc0de, llt_hash = 0xdeadc0dedeadc0de,
> llt_match_prefix = 0xdeadc0dedeadc0de,
> llt_free_entry = 0xdeadc0dedeadc0de, llt_foreach_entry =
> 0xdeadc0dedeadc0de, llt_link_entry = 0xdeadc0dedeadc0de,
> llt_unlink_entry = 0xdeadc0dedeadc0de, llt_fill_sa_entry =
> 0xdeadc0dedeadc0de,
> llt_free_tbl = 0xdeadc0dedeadc0de}
>
> :(
>
> Any ideas on where next to look?
>
> -adrian
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