Date: Mon, 15 Mar 1999 10:59:25 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Brian Feldman <green@unixhelp.org> Cc: Dmitrij Tejblum <dima@tejblum.dnttm.rssi.ru>, current@FreeBSD.ORG Subject: Re: Simple DOS against 3.x locks box solid Message-ID: <199903151859.KAA01757@apollo.backplane.com> References: <Pine.BSF.4.05.9903150654440.20897-100000@janus.syracuse.net>
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: :> Matthew Dillon wrote: :> > :> > We'll get a quick fix committed but the lockmgr stuff needs a real :> > going-over... having interrupts using the general lockmgr call is :> > a disaster waiting to happen. :> :> Hmmm. After I looked a bit further, it looks like a bug in the :> scheduler (?). Here is the stack trace: :> :> #9 0xc01ff64e in trap (frame={tf_es = 16, tf_ds = 16, tf_edi = 0, :> tf_esi = 16777216, tf_ebp = -999002708, tf_isp = -999002744, :> tf_ebx = -1071228500, tf_edx = -2, tf_ecx = 0, tf_eax = 0, :> tf_trapno = 12, tf_err = 0, tf_eip = -1072584332, tf_cs = 8, :... :> at ../../i386/i386/trap.c:195 :> #17 0xc01f5aa3 in swi_ast_user () :> :> the trap in swtch_com() (frame #15) is here: :> /* switch address space */ <----- line 622 :> movl %cr3,%ebx :> cmpl PCB_CR3(%edx),%ebx <----- trap :> je 4f :> :> I don't think this line is supposed to cause a trap... : :When it says "switch address space" What exactly do you think it's going to :do? What I mean is, I'm pretty certain this is a good trap =) : :The real problem did seem to be the NULL p dereference, as it was obvious :that it could happen in the code. I don't think the system is supposed to trap there. -Matt : FreeBSD: The Power to Serve! _ __ ___ ____ _____ |___/___/___/ Matthew Dillon <dillon@backplane.com> To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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