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Tue, 21 Jul 2020 14:45:40 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Date: Tue, 21 Jul 2020 14:37:28 -0000 From: Alexander Bulekov <1886362@bugs.launchpad.net> To: qemu-devel@nongnu.org X-Launchpad-Notification-Type: bug X-Launchpad-Bug: product=qemu; status=New; importance=Undecided; assignee=None; X-Launchpad-Bug-Information-Type: Public X-Launchpad-Bug-Private: no X-Launchpad-Bug-Security-Vulnerability: no X-Launchpad-Bug-Commenters: a1xndr jasowang philmd pjps pmaydell X-Launchpad-Bug-Reporter: Alexander Bulekov (a1xndr) X-Launchpad-Bug-Modifier: Alexander Bulekov (a1xndr) References: <159400349818.1851.7243060688419202620.malonedeb@wampee.canonical.com> <28d42c0f-99eb-a9c1-e3fc-98f11ee686ab@redhat.com> Message-ID: <20200721143723.zegwmuoyn6q75e5u@mozz.bu.edu> Subject: Re: [Bug 1886362] [NEW] Heap use-after-free in lduw_he_p through e1000e_write_to_rx_buffers X-Launchpad-Message-Rationale: Subscriber (QEMU) @qemu-devel-ml X-Launchpad-Message-For: qemu-devel-ml Precedence: bulk X-Generated-By: Launchpad (canonical.com); Revision="4809fcb62f445aaa3ae919f7f6c3cc7d156ea57a"; Instance="production-secrets-lazr.conf" X-Launchpad-Hash: 9508dd18a828360a479204a70e3c03aace4e1e1e Received-SPF: none client-ip=91.189.90.7; envelope-from=bounces@canonical.com; helo=indium.canonical.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/21 10:45:40 X-ACL-Warn: Detected OS = Linux 3.11 and newer [fuzzy] X-Spam_score_int: -58 X-Spam_score: -5.9 X-Spam_bar: ----- X-Spam_report: (-5.9 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=1, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Bug 1886362 <1886362@bugs.launchpad.net> Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Message-ID: <20200721143728.rhuU3nvRGTNlPMoNGw-V2uZHzL37w-8MgmWebxxMbw4@z> On 200721 1444, Peter Maydell wrote: > On Tue, 21 Jul 2020 at 14:21, Jason Wang wrote: > > On 2020/7/21 =E4=B8=8B=E5=8D=888:31, Peter Maydell wrote: > > > On Wed, 15 Jul 2020 at 09:36, Jason Wang wrote: > > >> I think the point is to make DMA to MMIO work as real hardware. > > > I wouldn't care to give a 100% guarantee that asking a real > > > h/w device to DMA to itself didn't cause it to misbehave :-) > > > It's more likely to happen-to-work because the DMA engine bit > > > of a real h/w device is going to be decoupled somewhat from > > > the respond-to-memory-transactions-for-registers logic, but > > > it probably wasn't something the designers were actively > > > thinking about either... > I searched around but couldn't find anything talking about this case for real hardware. I also looked at some HDL code for FPGAs that do DMA, but it seems most of the PCI DMA components are contained in proprietary IPs, though maybe I'm missing something (I've never programmed a DMA-capable FPGA). > > I think some device want such peer to peer transactions: > > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree= /Documentation/driver-api/pci/p2pdma.rst > = > That's a device DMAing to another device, not DMAing to *itself* > (device-to-another-device DMA should work fine in QEMU). And only > a very few devices will ever be sensible targets of the DMA -- > basically things like nvme that have a looks-like-memory area, > or special cases like doorbell registers. > = > > > Yeah, this is the interesting part for QEMU. How should we > > > structure devices that do DMA so that we can be sure that > > > the device emulation at least doesn't crash? We could have > > > a rule that all devices that do DMA must always postpone > > > all of that DMA to a bottom-half, but that's a lot of > > > refactoring of a lot of device code... > > > > > > It looks to me the issue happens only for device with loopback > = > I think in principle we have a problem for any device that > (a) has memory mapped registers and (b) does DMA reads > whose address is guest-controlled. Loopback isn't a > requirement -- if the guest programs, say, an RX descriptor > base address to point at the device's own registers, you > get exactly the same kind of unexpected-reentrancy. Could this be something that we check for in the pci_dma_* functions in hw/pci/pci.h? There we still have context about the source device for the dma read/write and could, compare addr against the device's PCI BARr's. Not sure about: 1.) How to do this without the overhead of convering the addr to a MemoryRegion, which is normally done, once, at the flatview_write stage. 2.) What to do if we catch such a DMA request? Quietly drop it? 3.) Non-PCI devices. I think this still doesn't cover the even crazier case where: CPU writes to DEV_A's MMIO DEV_A writes to DEV_B's MMIO DEV_B writes to DEV_A's MMIO and neither DEV_A or DEV_B use BHs... -Alex > thanks > -- PMM > -- = You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1886362 Title: Heap use-after-free in lduw_he_p through e1000e_write_to_rx_buffers Status in QEMU: New Bug description: Hello, This reproducer causes a heap-use-after free. QEMU Built with --enable-sa= nitizers: cat << EOF | ./i386-softmmu/qemu-system-i386 -M q35,accel=3Dqtest \ -qtest stdio -nographic -monitor none -serial none outl 0xcf8 0x80001010 outl 0xcfc 0xe1020000 outl 0xcf8 0x80001014 outl 0xcf8 0x80001004 outw 0xcfc 0x7 outl 0xcf8 0x800010a2 write 0xe102003b 0x1 0xff write 0xe1020103 0x1e 0xffffff055c5e5c30be4511d084fffffffffffffffffffffff= fffffffffff write 0xe1020420 0x4 0xffffffff write 0xe1020424 0x4 0xffffffff write 0xe102042b 0x1 0xff write 0xe1020430 0x4 0x055c5e5c write 0x5c041 0x1 0x04 write 0x5c042 0x1 0x02 write 0x5c043 0x1 0xe1 write 0x5c048 0x1 0x8a write 0x5c04a 0x1 0x31 write 0x5c04b 0x1 0xff write 0xe1020403 0x1 0xff EOF The Output: =3D=3D22689=3D=3DERROR: AddressSanitizer: heap-use-after-free on address = 0x62500026800e at pc 0x55b93bb18bfa bp 0x7fffdbe844f0 sp 0x7fffdbe83cb8 READ of size 2 at 0x62500026800e thread T0 #0 in __asan_memcpy (/build/i386-softmmu/qemu-system-i386+) #1 in lduw_he_p /include/qemu/bswap.h:332:5 #2 in ldn_he_p /include/qemu/bswap.h:550:1 #3 in flatview_write_continue /exec.c:3145:19 #4 in flatview_write /exec.c:3186:14 #5 in address_space_write /exec.c:3280:18 #6 in address_space_rw /exec.c:3290:16 #7 in dma_memory_rw_relaxed /include/sysemu/dma.h:87:18 #8 in dma_memory_rw /include/sysemu/dma.h:113:12 #9 in pci_dma_rw /include/hw/pci/pci.h:789:5 #10 in pci_dma_write /include/hw/pci/pci.h:802:12 #11 in e1000e_write_to_rx_buffers /hw/net/e1000e_core.c:1412:9 #12 in e1000e_write_packet_to_guest /hw/net/e1000e_core.c:1582:21 #13 in e1000e_receive_iov /hw/net/e1000e_core.c:1709:9 #14 in e1000e_nc_receive_iov /hw/net/e1000e.c:213:12 #15 in net_tx_pkt_sendv /hw/net/net_tx_pkt.c:544:9 #16 in net_tx_pkt_send /hw/net/net_tx_pkt.c:620:9 #17 in net_tx_pkt_send_loopback /hw/net/net_tx_pkt.c:633:11 #18 in e1000e_tx_pkt_send /hw/net/e1000e_core.c:664:16 #19 in e1000e_process_tx_desc /hw/net/e1000e_core.c:743:17 #20 in e1000e_start_xmit /hw/net/e1000e_core.c:934:9 #21 in e1000e_set_tctl /hw/net/e1000e_core.c:2431:9 #22 in e1000e_core_write /hw/net/e1000e_core.c:3265:9 #23 in e1000e_mmio_write /hw/net/e1000e.c:109:5 #24 in memory_region_write_accessor /memory.c:483:5 #25 in access_with_adjusted_size /memory.c:544:18 #26 in memory_region_dispatch_write /memory.c:1476:16 #27 in flatview_write_continue /exec.c:3146:23 #28 in flatview_write /exec.c:3186:14 #29 in address_space_write /exec.c:3280:18 #30 in qtest_process_command /qtest.c:567:9 #31 in qtest_process_inbuf /qtest.c:710:9 #32 in qtest_read /qtest.c:722:5 #33 in qemu_chr_be_write_impl /chardev/char.c:188:9 #34 in qemu_chr_be_write /chardev/char.c:200:9 #35 in fd_chr_read /chardev/char-fd.c:68:9 #36 in qio_channel_fd_source_dispatch /io/channel-watch.c:84:12 #37 in g_main_context_dispatch (/usr/lib/x86_64-linux-gnu/libglib-2.= 0.so.0+) #38 in glib_pollfds_poll /util/main-loop.c:219:9 #39 in os_host_main_loop_wait /util/main-loop.c:242:5 #40 in main_loop_wait /util/main-loop.c:518:11 #41 in qemu_main_loop /softmmu/vl.c:1664:9 #42 in main /softmmu/main.c:52:5 #43 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+) #44 in _start (/build/i386-softmmu/qemu-system-i386+) 0x62500026800e is located 14 bytes inside of 138-byte region [0x625000268= 000,0x62500026808a) freed by thread T0 here: #0 in free (/build/i386-softmmu/qemu-system-i386+) #1 in qemu_vfree /util/oslib-posix.c:238:5 #2 in address_space_unmap /exec.c:3616:5 #3 in dma_memory_unmap /include/sysemu/dma.h:148:5 #4 in pci_dma_unmap /include/hw/pci/pci.h:839:5 #5 in net_tx_pkt_reset /hw/net/net_tx_pkt.c:453:9 #6 in e1000e_process_tx_desc /hw/net/e1000e_core.c:749:9 #7 in e1000e_start_xmit /hw/net/e1000e_core.c:934:9 #8 in e1000e_set_tctl /hw/net/e1000e_core.c:2431:9 #9 in e1000e_core_write /hw/net/e1000e_core.c:3265:9 #10 in e1000e_mmio_write /hw/net/e1000e.c:109:5 #11 in memory_region_write_accessor /memory.c:483:5 #12 in access_with_adjusted_size /memory.c:544:18 #13 in memory_region_dispatch_write /memory.c:1476:16 #14 in flatview_write_continue /exec.c:3146:23 #15 in flatview_write /exec.c:3186:14 #16 in address_space_write /exec.c:3280:18 #17 in address_space_rw /exec.c:3290:16 #18 in dma_memory_rw_relaxed /include/sysemu/dma.h:87:18 #19 in dma_memory_rw /include/sysemu/dma.h:113:12 #20 in pci_dma_rw /include/hw/pci/pci.h:789:5 #21 in pci_dma_write /include/hw/pci/pci.h:802:12 #22 in e1000e_write_to_rx_buffers /hw/net/e1000e_core.c:1412:9 #23 in e1000e_write_packet_to_guest /hw/net/e1000e_core.c:1582:21 #24 in e1000e_receive_iov /hw/net/e1000e_core.c:1709:9 #25 in e1000e_nc_receive_iov /hw/net/e1000e.c:213:12 #26 in net_tx_pkt_sendv /hw/net/net_tx_pkt.c:544:9 #27 in net_tx_pkt_send /hw/net/net_tx_pkt.c:620:9 #28 in net_tx_pkt_send_loopback /hw/net/net_tx_pkt.c:633:11 #29 in e1000e_tx_pkt_send /hw/net/e1000e_core.c:664:16 previously allocated by thread T0 here: #0 in posix_memalign (/build/i386-softmmu/qemu-system-i386+) #1 in qemu_try_memalign /util/oslib-posix.c:198:11 #2 in qemu_memalign /util/oslib-posix.c:214:27 #3 in address_space_map /exec.c:3558:25 #4 in dma_memory_map /include/sysemu/dma.h:138:9 #5 in pci_dma_map /include/hw/pci/pci.h:832:11 #6 in net_tx_pkt_add_raw_fragment /hw/net/net_tx_pkt.c:391:24 #7 in e1000e_process_tx_desc /hw/net/e1000e_core.c:731:14 #8 in e1000e_start_xmit /hw/net/e1000e_core.c:934:9 #9 in e1000e_set_tctl /hw/net/e1000e_core.c:2431:9 #10 in e1000e_core_write /hw/net/e1000e_core.c:3265:9 #11 in e1000e_mmio_write /hw/net/e1000e.c:109:5 #12 in memory_region_write_accessor /memory.c:483:5 #13 in access_with_adjusted_size /memory.c:544:18 #14 in memory_region_dispatch_write /memory.c:1476:16 #15 in flatview_write_continue /exec.c:3146:23 #16 in flatview_write /exec.c:3186:14 #17 in address_space_write /exec.c:3280:18 #18 in qtest_process_command /qtest.c:567:9 #19 in qtest_process_inbuf /qtest.c:710:9 #20 in qtest_read /qtest.c:722:5 #21 in qemu_chr_be_write_impl /chardev/char.c:188:9 #22 in qemu_chr_be_write /chardev/char.c:200:9 #23 in fd_chr_read /chardev/char-fd.c:68:9 #24 in qio_channel_fd_source_dispatch /io/channel-watch.c:84:12 #25 in g_main_context_dispatch (/usr/lib/x86_64-linux-gnu/libglib-2.= 0.so.0+) -Alex To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1886362/+subscriptions