Date: Fri, 10 Jan 2014 00:17:12 +0200 From: Guy Yur <guyyur@gmail.com> To: Gleb Smirnoff <glebius@freebsd.org> Cc: freebsd-net@freebsd.org, freebsd-arm@freebsd.org Subject: Re: 10.0-RC1, armv6: "pfctl -s state" crashes on BeagleBone Black due to unaligned access Message-ID: <CAC67Hz-Rz557COtyE1AurduZrstOqaMaA_H9VzBypsaHfSc=cg@mail.gmail.com> In-Reply-To: <20140109104223.GS71033@FreeBSD.org> References: <CAC67Hz_QXcHHSFOLLgUGqLWRQpzhRRv_b%2BWGMMQsfk-VQp74RA@mail.gmail.com> <20140109104223.GS71033@FreeBSD.org>
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Hi, On Thu, Jan 9, 2014 at 12:42 PM, Gleb Smirnoff <glebius@freebsd.org> wrote: > Guy, > > On Sat, Jan 04, 2014 at 03:06:02PM +0200, Guy Yur wrote: > G> I am running 10.0-RC1 arm.armv6 on the BeagleBone Black. > G> The "pfctl -s state" command is crashing when trying to print the > G> second entry. > G> > G> (gdb) bt > G> #0 print_host (addr=0x2085a11a, port=7660, af=2 '\002', opts=1024) at > G> /usr/src/sbin/pfctl/pf_print_state.c:178 > G> #1 0x00021c4c in print_state (s=0x2085a0f2, opts=1024) at > G> /usr/src/sbin/pfctl/pf_print_state.c:236 > G> #2 0x0000c664 in pfctl_show_states (dev=<value optimized out>, > G> iface=0x0, opts=1024) at /usr/src/sbin/pfctl/pfctl.c:1095 > G> > G> sizeof(struct pfsync_state_key) is 36 > G> sizeof(struct pfsync_state_peer) is 32 > G> sizeof(struct pf_addr) is 16 > G> sizeof(struct pfsync_state) is 242 > G> > > I will try to fix this making new structure for the ioctl. That will mean > moving slowly towards divorcing internal structures and ioctl ones. > > I'd appreciate if you file a PR on that, so that problem won't leave forgotten > in the mailing list. You can even code the bugfix :) > > Thanks! > > -- > Totus tuus, Glebius. I filled arm/185617 with some updated information. After further looking at why the kernel doesn't crash when filling the pfsync_state array and only the userspace pfctl is crashing I see that pfsync_state has the __packed attribute which means on arm unaligned access is used so there is no problem handling an unaligned pfsync_state. The reason pfctl crashes is because it passes a structure field as a pf_addr pointer. struct pf_addr is not __packed so on arm word access will be used, triggering the unaligned fault. So there is indeed no need to break the pfsync protocol. In if_pfsync.c I think all the accesses to pfsync_state are done using a pfsync_state pointer, there is no passing of struct fields as separate pointers and since the struct is covered by __packed there won't be an unaligned access. Thanks, Guy
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