Qemu Qemu 2.4.0 Rc2

A flaw was found in QEMU. An assertion failure was present in the update_sctp_checksum() function in hw/net/net_tx_pkt.c when trying to calculate the checksum of a short-sized fragmented packet. This flaw allows a malicious guest to crash QEMU and cause a denial of service condition.

QEMU before 8.2.0 has an integer underflow, and resultant buffer overflow, via a TI command when an expected non-DMA transfer length is less than the length of the available FIFO data. This occurs in esp_do_nodma in hw/scsi/esp.c because of an underflow of async_len.

An issue was discovered in QEMU 7.1.0 through 8.2.1. register_vfs in hw/pci/pcie_sriov.c does not set NumVFs to PCI_SRIOV_TOTAL_VF, and thus interaction with hw/nvme/ctrl.c is mishandled.

An issue was discovered in QEMU 7.1.0 through 8.2.1. register_vfs in hw/pci/pcie_sriov.c mishandles the situation where a guest writes NumVFs greater than TotalVFs, leading to a buffer overflow in VF implementations.

A flaw was found in the QEMU built-in VNC server while processing ClientCutText messages. The qemu_clipboard_request() function can be reached before vnc_server_cut_text_caps() was called and had the chance to initialize the clipboard peer, leading to a NULL pointer dereference. This could allow a malicious authenticated VNC client to crash QEMU and trigger a denial of service.

A stack based buffer overflow was found in the virtio-net device of QEMU. This issue occurs when flushing TX in the virtio_net_flush_tx function if guest features VIRTIO_NET_F_HASH_REPORT, VIRTIO_F_VERSION_1 and VIRTIO_NET_F_MRG_RXBUF are enabled. This could allow a malicious user to overwrite local variables allocated on the stack. Specifically, the `out_sg` variable could be used to read a part of process memory and send it to the wire, causing an information leak.

A flaw was found in the 9p passthrough filesystem (9pfs) implementation in QEMU. The 9pfs server did not prohibit opening special files on the host side, potentially allowing a malicious client to escape from the exported 9p tree by creating and opening a device file in the shared folder.

A bug in QEMU could cause a guest I/O operation otherwise addressed to an arbitrary disk offset to be targeted to offset 0 instead (potentially overwriting the VM's boot code). This could be used, for example, by L2 guests with a virtual disk (vdiskL2) stored on a virtual disk of an L1 (vdiskL1) hypervisor to read and/or write data to LBA 0 of vdiskL1, potentially gaining control of L1 at its next reboot.

A flaw was found in QEMU. The async nature of hot-unplug enables a race scenario where the net device backend is cleared before the virtio-net pci frontend has been unplugged. A malicious guest could use this time window to trigger an assertion and cause a denial of service.

A flaw was found in the QEMU built-in VNC server while processing ClientCutText messages. A wrong exit condition may lead to an infinite loop when inflating an attacker controlled zlib buffer in the `inflate_buffer` function. This could allow a remote authenticated client who is able to send a clipboard to the VNC server to trigger a denial of service.

QEMU through 8.0.0 could trigger a division by zero in scsi_disk_reset in hw/scsi/scsi-disk.c because scsi_disk_emulate_mode_select does not prevent s->qdev.blocksize from being 256. This stops QEMU and the guest immediately.

The hardware emulation in the of_dpa_cmd_add_l2_flood of rocker device model in QEMU, as used in 7.0.0 and earlier, allows remote attackers to crash the host qemu and potentially execute code on the host via execute a malformed program in the guest OS. Note: This has been disputed by multiple third parties as not a valid vulnerability due to the rocker device not falling within the virtualization use case.

QEMU through 8.0.4 accesses a NULL pointer in nvme_directive_receive in hw/nvme/ctrl.c because there is no check for whether an endurance group is configured before checking whether Flexible Data Placement is enabled.

A heap out-of-bounds memory read flaw was found in the virtual nvme device in QEMU. The QEMU process does not validate an offset provided by the guest before computing a host heap pointer, which is used for copying data back to the guest. Arbitrary heap memory relative to an allocated buffer can be disclosed.

A flaw was found in the QEMU virtual crypto device while handling data encryption/decryption requests in virtio_crypto_handle_sym_req. There is no check for the value of `src_len` and `dst_len` in virtio_crypto_sym_op_helper, potentially leading to a heap buffer overflow when the two values differ.

A DMA reentrancy issue leading to a use-after-free error was found in the e1000e NIC emulation code in QEMU. This issue could allow a privileged guest user to crash the QEMU process on the host, resulting in a denial of service.

A flaw was found in the QEMU built-in VNC server. When a client connects to the VNC server, QEMU checks whether the current number of connections crosses a certain threshold and if so, cleans up the previous connection. If the previous connection happens to be in the handshake phase and fails, QEMU cleans up the connection again, resulting in a NULL pointer dereference issue. This could allow a remote unauthenticated client to cause a denial of service.

A flaw was found in the QEMU Guest Agent service for Windows. A local unprivileged user may be able to manipulate the QEMU Guest Agent's Windows installer via repair custom actions to elevate their privileges on the system.

A flaw was found in the QEMU implementation of VMWare's paravirtual RDMA device. This flaw allows a crafted guest driver to allocate and initialize a huge number of page tables to be used as a ring of descriptors for CQ and async events, potentially leading to an out-of-bounds read and crash of QEMU.

A vulnerability in the lsi53c895a device affects the latest version of qemu. A DMA-MMIO reentrancy problem may lead to memory corruption bugs like stack overflow or use-after-free.

An out-of-bounds read flaw was found in the QXL display device emulation in QEMU. The qxl_phys2virt() function does not check the size of the structure pointed to by the guest physical address, potentially reading past the end of the bar space into adjacent pages. A malicious guest user could use this flaw to crash the QEMU process on the host causing a denial of service condition.

An off-by-one read/write issue was found in the SDHCI device of QEMU. It occurs when reading/writing the Buffer Data Port Register in sdhci_read_dataport and sdhci_write_dataport, respectively, if data_count == block_size. A malicious guest could use this flaw to crash the QEMU process on the host, resulting in a denial of service condition.

An integer underflow issue was found in the QEMU VNC server while processing ClientCutText messages in the extended format. A malicious client could use this flaw to make QEMU unresponsive by sending a specially crafted payload message, resulting in a denial of service.

A DMA reentrancy issue was found in the Tulip device emulation in QEMU. When Tulip reads or writes to the rx/tx descriptor or copies the rx/tx frame, it doesn't check whether the destination address is its own MMIO address. This can cause the device to trigger MMIO handlers multiple times, possibly leading to a stack or heap overflow. A malicious guest could use this flaw to crash the QEMU process on the host, resulting in a denial of service condition.

A flaw was found in the QEMU virtio-fs shared file system daemon (virtiofsd) implementation. This flaw is strictly related to CVE-2018-13405. A local guest user can create files in the directories shared by virtio-fs with unintended group ownership in a scenario where a directory is SGID to a certain group and is writable by a user who is not a member of the group. This could allow a malicious unprivileged user inside the guest to gain access to resources accessible to the root group, potentially escalating their privileges within the guest. A malicious local user in the host might also leverage this unexpected executable file created by the guest to escalate their privileges on the host system.