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[88.10.102.251]) by smtp.gmail.com with ESMTPSA id q19sm2843978wra.89.2019.08.29.08.43.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 29 Aug 2019 08:43:52 -0700 (PDT) To: Samuel Thibault , slirp@lists.freedesktop.org, Petr Matousek , Vishnu Dev TJ , qemu-stable@nongnu.org, qemu-devel@nongnu.org, Prasad J Pandit References: <20190822144134.23521-1-philmd@redhat.com> <20190822144134.23521-2-philmd@redhat.com> <20190822183313.pptfwjsnrpdi6tfp@function> <14216968-a066-6abf-1952-3cff3aa3eee3@redhat.com> <20190825225403.vwg2fhfff6i7gnwd@function> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Openpgp: id=89C1E78F601EE86C867495CBA2A3FD6EDEADC0DE; url=http://pgp.mit.edu/pks/lookup?op=get&search=0xA2A3FD6EDEADC0DE Message-ID: Date: Thu, 29 Aug 2019 17:43:51 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190825225403.vwg2fhfff6i7gnwd@function> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [Slirp] [PATCH 1/2] Do not reassemble fragments pointing outside of the original payload X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Samuel, On 8/26/19 12:54 AM, Samuel Thibault wrote: > Hello, >=20 > Philippe Mathieu-Daud=E9, le ven. 23 ao=FBt 2019 17:15:32 +0200, a ecri= t: >>> Did you make your test with commit 126c04acbabd ("Fix heap overflow i= n >>> ip_reass on big packet input") applied? >> >> Yes, unfortunately it doesn't fix the issue. >=20 > Ok. >=20 > Could you try the attached patch? There was a use-after-free. Without > it, I can indeed crash qemu with the given exploit. With it I don't > seem to be able to crash it (trying in a loop for several minutes). No change with your patch applied: Thread 4 "qemu-system-x86" received signal SIGSEGV, Segmentation fault. [Switching to Thread 0x7fffe94c4700 (LWP 14031)] 0x0000555555e835c5 in icmp_input (m=3D0x0, hlen=3D20) at qemu/slirp/src/ip_icmp.c:130 130 register struct ip *ip =3D mtod(m, struct ip *); (gdb) bt #0 0x0000555555e835c5 in icmp_input (m=3D0x0, hlen=3D20) at qemu/slirp/src/ip_icmp.c:130 #1 0x0000555555e85450 in ip_input (m=3D0x0) at qemu/slirp/src/ip_input.c= :205 #2 0x0000555555e723d2 in slirp_input (slirp=3D0x555556708170, pkt=3D0x55555727fab0 "", pkt_len=3D1314) at qemu/slirp/src/slirp.c:785 #3 0x0000555555c83961 in net_slirp_receive (nc=3D0x555556707fa0, buf=3D0x55555727fab0 "", size=3D1314) at qemu/net/slirp.c:126 #4 0x0000555555c788cb in nc_sendv_compat (nc=3D0x555556707fa0, iov=3D0x7fffe94c0930, iovcnt=3D1, flags=3D0) at qemu/net/net.c:700 #5 0x0000555555c7898d in qemu_deliver_packet_iov (sender=3D0x5555566a6440, flags=3D0, iov=3D0x7fffe94c0930, iovcnt=3D1, opaque=3D0x555556707fa0) at qemu/net/net.c:728 #6 0x0000555555c7b49d in qemu_net_queue_deliver_iov (queue=3D0x5555566a6260, sender=3D0x5555566a6440, flags=3D0, iov=3D0x7fffe94c0930, iovcnt=3D1) at qemu/net/queue.c:179 #7 0x0000555555c7b60c in qemu_net_queue_send_iov (queue=3D0x5555566a6260= , sender=3D0x5555566a6440, flags=3D0, iov=3D0x7fffe94c0930, iovcnt=3D1, sent_cb=3D0x0) at qemu/net/queue.c:224 #8 0x0000555555c78ad2 in qemu_sendv_packet_async (sender=3D0x5555566a6440, iov=3D0x7fffe94c0930, iovcnt=3D1, sent_cb=3D0x0= ) at qemu/net/net.c:769 #9 0x0000555555c78aff in qemu_sendv_packet (nc=3D0x5555566a6440, iov=3D0x7fffe94c0930, iovcnt=3D1) at qemu/net/net.c:777 #10 0x0000555555c7c038 in net_hub_receive_iov (hub=3D0x5555566b1ab0, source_port=3D0x5555566a67a0, iov=3D0x7fffe94c0930, iovcnt=3D1) at qemu/net/hub.c:74 #11 0x0000555555c7c232 in net_hub_port_receive_iov (nc=3D0x5555566a67a0, iov=3D0x7fffe94c0930, iovcnt=3D1) at qemu/net/hub.c:125 #12 0x0000555555c78972 in qemu_deliver_packet_iov (sender=3D0x555557292860, flags=3D0, iov=3D0x7fffe94c0930, iovcnt=3D1, opaque=3D0x5555566a67a0) at qemu/net/net.c:726 #13 0x0000555555c7b421 in qemu_net_queue_deliver (queue=3D0x5555566a6940, sender=3D0x555557292860, flags=3D0, data=3D0x55555727fab0 "", size=3D1314= ) at qemu/net/queue.c:164 #14 0x0000555555c7b53d in qemu_net_queue_send (queue=3D0x5555566a6940, sender=3D0x555557292860, flags=3D0, data=3D0x55555727fab0 "", size=3D1314= , sent_cb=3D0x0) at qemu/net/queue.c:199 #15 0x0000555555c78733 in qemu_send_packet_async_with_flags (sender=3D0x555557292860, flags=3D0, buf=3D0x55555727fab0 "", size=3D1314= , sent_cb=3D0x0) at qemu/net/net.c:654 #16 0x0000555555c7876b in qemu_send_packet_async (sender=3D0x555557292860= , buf=3D0x55555727fab0 "", size=3D1314, sent_cb=3D0x0) at qemu/net/net.c:66= 1 #17 0x0000555555c78798 in qemu_send_packet (nc=3D0x555557292860, buf=3D0x55555727fab0 "", size=3D1314) at qemu/net/net.c:667 #18 0x0000555555b32b67 in e1000_send_packet (s=3D0x55555725ce00, buf=3D0x55555727fab0 "", size=3D1314) at qemu/hw/net/e1000.c:552 #19 0x0000555555b32fd3 in xmit_seg (s=3D0x55555725ce00) at qemu/hw/net/e1000.c:615 #20 0x0000555555b33503 in process_tx_desc (s=3D0x55555725ce00, dp=3D0x7fffe94c0b70) at qemu/hw/net/e1000.c:702 #21 0x0000555555b336fb in start_xmit (s=3D0x55555725ce00) at qemu/hw/net/e1000.c:757 #22 0x0000555555b347b5 in set_tctl (s=3D0x55555725ce00, index=3D3590, val= =3D8) at qemu/hw/net/e1000.c:1128 #23 0x0000555555b34932 in e1000_mmio_write (opaque=3D0x55555725ce00, addr=3D14360, val=3D8, size=3D4) at qemu/hw/net/e1000.c:1304 #24 0x000055555585b126 in memory_region_write_accessor (mr=3D0x55555725f700, addr=3D14360, value=3D0x7fffe94c0cd8, size=3D4, shi= ft=3D0, mask=3D4294967295, attrs=3D...) at qemu/memory.c:507 #25 0x000055555585b336 in access_with_adjusted_size (addr=3D14360, value=3D0x7fffe94c0cd8, size=3D4, access_size_min=3D4, access_size_max=3D= 4, access_fn=3D0x55555585b03d , mr=3D0x55555725f700, attrs=3D...) at qemu/memory.c:573 #26 0x000055555585e315 in memory_region_dispatch_write (mr=3D0x55555725f700, addr=3D14360, data=3D8, size=3D4, attrs=3D...) at qemu/memory.c:1509 #27 0x00005555557fcee2 in flatview_write_continue (fv=3D0x7fffe02307f0, addr=3D4273747992, attrs=3D..., buf=3D0x7ffff7fcb028 "\b", len=3D4, addr1= =3D14360, l=3D4, mr=3D0x55555725f700) at qemu/exec.c:3367 #28 0x00005555557fd027 in flatview_write (fv=3D0x7fffe02307f0, addr=3D4273747992, attrs=3D..., buf=3D0x7ffff7fcb028 "\b", len=3D4) at qemu/exec.c:3406 #29 0x00005555557fd32c in address_space_write (as=3D0x55555641e640 , addr=3D4273747992, attrs=3D..., buf=3D0x7ffff7fcb= 028 "\b", len=3D4) at qemu/exec.c:3496 #30 0x00005555557fd37e in address_space_rw (as=3D0x55555641e640 , addr=3D4273747992, attrs=3D..., buf=3D0x7ffff7fcb= 028 "\b", len=3D4, is_write=3Dtrue) at qemu/exec.c:3507 #31 0x0000555555876629 in kvm_cpu_exec (cpu=3D0x55555670e860) at qemu/accel/kvm/kvm-all.c:2288 #32 0x000055555584c1d8 in qemu_kvm_cpu_thread_fn (arg=3D0x55555670e860) a= t qemu/cpus.c:1290 #33 0x0000555555e48991 in qemu_thread_start (args=3D0x5555567328a0) at qemu/util/qemu-thread-posix.c:502 Note 1: To trigger this I have to build with: ./configure --extra-cflags=3D-ggdb --enable-debug --enable-sanitizers Using different combinations I can not reproduce the crash. Note 2: We miss some Makefile rules in QEMU with the libslirp split. Checkouting branches in the slirp/ directory doesn't trigger recompiling the slirp object, and even if I force the creation of the libslirp.a archive, the QEMU binaries are not linked again with the refreshed archiv= e.