Date: Wed, 21 Oct 2009 09:27:28 +0100 (BST) From: Robert Watson <rwatson@FreeBSD.org> To: Qing Li <qingli@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r198301 - head/sys/netinet Message-ID: <alpine.BSF.2.00.0910210927080.24137@fledge.watson.org> In-Reply-To: <9ace436c0910210110gc359cd1jea3dbd49db7e8733@mail.gmail.com> References: <200910201755.n9KHtgT9073966@svn.freebsd.org> <alpine.BSF.2.00.0910210853540.24137@fledge.watson.org> <9ace436c0910210110gc359cd1jea3dbd49db7e8733@mail.gmail.com>
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This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --621616949-69947553-1256113648=:24137 Content-Type: TEXT/PLAIN; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8BIT On Wed, 21 Oct 2009, Qing Li wrote: > I believe this patch will fix your crash. Sounds good, thanks! Robert > > -- Qing > > > On Wed, Oct 21, 2009 at 12:58 AM, Robert Watson <rwatson@freebsd.org> wrote: >> On Tue, 20 Oct 2009, Qing Li wrote: >> >>> In the ARP callout timer expiration function, the current time_second >>> is compared against the entry expiration time value (that was set based >>> on time_second) to check if the current time is larger than the set >>> expiration time. Due to the +/- timer granularity value, the comparison >>> returns false, causing the alternative code to be executed. The >>> alternative code path freed the memory without removing that entry >>> from the table list, causing a use-after-free bug. >>> >>> Reviewed by: discussed with kmacy >>> MFC after: immediately >>> Verified by: rnoland, yongari >> >> Could this be the same problem I ran into overnight on an 18 October kernel: >> >> Fatal trap 12: page fault while in kernel mode >> cpuid = 0; apic id = 00 >> fault virtual address = 0x7572749f >> fault code = supervisor read, page not present >> instruction pointer = 0x20:0xc09c0551 >> stack pointer = 0x28:0xc43f6ab4 >> frame pointer = 0x28:0xc43f6adc >> code segment = base 0x0, limit 0xfffff, type 0x1b >> = DPL 0, pres 1, def32 1, gran 1 >> processor eflags = interrupt enabled, resume, IOPL = 0 >> current process = 0 (em0 taskq) >> >> #9 0xc0be731b in calltrap () at ../../../i386/i386/exception.s:165 >> #10 0xc09c0551 in in_lltable_lookup (llt=0xc4955200, flags=8192, >> l3addr=0xc43f6b60) at ../../../netinet/in.c:1361 >> #11 0xc09b8ea7 in arpintr (m=0xc48dcd00) at if_llatbl.h:202 >> #12 0xc096f899 in netisr_dispatch_src (proto=7, source=0, m=0xc48dcd00) >> at ../../../net/netisr.c:917 >> #13 0xc096fb30 in netisr_dispatch (proto=7, m=0xc48dcd00) >> at ../../../net/netisr.c:1004 >> #14 0xc0967c11 in ether_demux (ifp=0xc470b400, m=0xc48dcd00) >> at ../../../net/if_ethersubr.c:895 >> #15 0xc0968163 in ether_input (ifp=0xc470b400, m=0xc48dcd00) >> at ../../../net/if_ethersubr.c:754 >> #16 0xc063bcaa in em_rxeof (adapter=0xc470d000, count=99) >> at ../../../dev/e1000/if_em.c:4610 >> #17 0xc063dfc7 in em_handle_rxtx (context=0xc470d000, pending=1) >> at ../../../dev/e1000/if_em.c:1763 >> >> (kgdb) frame 10 >> #10 0xc09c0551 in in_lltable_lookup (llt=0xc4955200, flags=8192, >> l3addr=0xc43f6b60) at ../../../netinet/in.c:1361 >> 1361 LIST_FOREACH(lle, lleh, lle_next) { >> (kgdb) list >> 1356 KASSERT(l3addr->sa_family == AF_INET, >> 1357 ("sin_family %d", l3addr->sa_family)); >> 1358 >> 1359 hashkey = sin->sin_addr.s_addr; >> 1360 lleh = &llt->lle_head[LLATBL_HASH(hashkey, LLTBL_HASHMASK)]; >> 1361 LIST_FOREACH(lle, lleh, lle_next) { >> 1362 struct sockaddr_in *sa2 = (struct sockaddr_in >> *)L3_ADDR(lle); >> 1363 if (lle->la_flags & LLE_DELETED) >> 1364 continue; >> 1365 if (sa2->sin_addr.s_addr == sin->sin_addr.s_addr) >> (kgdb) print *llt >> $5 = {llt_link = {sle_next = 0x0}, lle_head = {{lh_first = 0xc760d580}, { >> lh_first = 0x0}, {lh_first = 0x0}, {lh_first = 0xc75c3900}, { >> lh_first = 0x0} <repeats 14 times>, {lh_first = 0xc49a8380}, { >> lh_first = 0x0}, {lh_first = 0x0}, {lh_first = 0x0}, {lh_first = 0x0}, >> { >> lh_first = 0x0}, {lh_first = 0x0}, {lh_first = 0x0}, {lh_first = 0x0}, >> { >> lh_first = 0x0}, {lh_first = 0xc61be780}, {lh_first = 0x0}, { >> lh_first = 0x0}, {lh_first = 0x0}}, llt_af = 2, llt_ifp = 0xc470b400, >> llt_new = 0xc09bdd60 <in_lltable_new>, >> llt_free = 0xc09c0490 <in_lltable_free>, >> llt_prefix_free = 0xc09c09b0 <in_lltable_prefix_free>, >> llt_lookup = 0xc09c0510 <in_lltable_lookup>, >> llt_rtcheck = 0xc09bdbe0 <in_lltable_rtcheck>, >> llt_dump = 0xc09bd9c0 <in_lltable_dump>} >> (kgdb) print *l3addr >> $6 = {sa_len = 16 '\020', sa_family = 2 '\002', >> sa_data = "\000\000??*\001\000\000\000\000\000\000\000"} >> (kgdb) print lle >> $7 = (struct llentry *) 0x75727473 >> (kgdb) print lleh >> $8 = (struct llentries *) 0xc4955210 >> (kgdb) print *lleh >> $9 = {lh_first = 0xc75c3900} >> >> Your commit was after this kernel, so I'd be quite happy with the answer >> "now fixed" but wanted to be sure. >> >> Robert >> >>> >>> Modified: >>> head/sys/netinet/if_ether.c >>> >>> Modified: head/sys/netinet/if_ether.c >>> >>> ============================================================================== >>> --- head/sys/netinet/if_ether.c Tue Oct 20 17:50:36 2009 (r198300) >>> +++ head/sys/netinet/if_ether.c Tue Oct 20 17:55:42 2009 (r198301) >>> @@ -175,18 +175,18 @@ arptimer(void *arg) >>> CURVNET_SET(ifp->if_vnet); >>> IF_AFDATA_LOCK(ifp); >>> LLE_WLOCK(lle); >>> - if (((lle->la_flags & LLE_DELETED) || >>> - (time_second >= lle->la_expire)) && >>> - (!callout_pending(&lle->la_timer) && >>> + if ((!callout_pending(&lle->la_timer) && >>> callout_active(&lle->la_timer))) { >>> (void) llentry_free(lle); >>> ARPSTAT_INC(timeouts); >>> - } else { >>> - /* >>> - * Still valid, just drop our reference >>> - */ >>> - LLE_FREE_LOCKED(lle); >>> + } >>> +#ifdef DIAGNOSTICS >>> + else { >>> + struct sockaddr *l3addr = L3_ADDR(lle); >>> + log(LOG_INFO, "arptimer issue: %p, IPv4 address: >>> \"%s\"\n", lle, >>> + inet_ntoa(((const struct sockaddr_in >>> *)l3addr)->sin_addr)); >>> } >>> +#endif >>> IF_AFDATA_UNLOCK(ifp); >>> CURVNET_RESTORE(); >>> } >>> @@ -377,7 +377,7 @@ retry: >>> >>> if (renew) { >>> LLE_ADDREF(la); >>> - la->la_expire = time_second; >>> + la->la_expire = time_second + V_arpt_down; >>> callout_reset(&la->la_timer, hz * V_arpt_down, arptimer, >>> la); >>> la->la_asked++; >>> LLE_WUNLOCK(la); >>> >> > --621616949-69947553-1256113648=:24137--
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