An issue was discovered in Xen through 4.14.x. There is a lack of preemption in evtchn_reset() / evtchn_destroy(). In particular, the FIFO event channel model allows guests to have a large number of event channels active at a time. Closing all of these (when resetting all event channels or when cleaning up after the guest) may take extended periods of time. So far, there was no arrangement for preemption at suitable intervals, allowing a CPU to spend an almost unbounded amount of time in the processing of these operations. Malicious or buggy guest kernels can mount a Denial of Service (DoS) attack affecting the entire system. All Xen versions are vulnerable in principle. Whether versions 4.3 and older are vulnerable depends on underlying hardware characteristics.

A flaw was found in the spice-vdagentd daemon, where it did not properly handle client connections that can be established via the UNIX domain socket in `/run/spice-vdagentd/spice-vdagent-sock`. Any unprivileged local guest user could use this flaw to prevent legitimate agents from connecting to the spice-vdagentd daemon, resulting in a denial of service. The highest threat from this vulnerability is to system availability. This flaw affects spice-vdagent versions 0.20 and prior.

A NULL pointer dereference flaw was found in the Linux kernel's GPU Nouveau driver functionality in versions prior to 5.12-rc1 in the way the user calls ioctl DRM_IOCTL_NOUVEAU_CHANNEL_ALLOC. This flaw allows a local user to crash the system.

An issue was discovered in Xen through 4.14.x. There is mishandling of the constraint that once-valid event channels may not turn invalid. Logic in the handling of event channel operations in Xen assumes that an event channel, once valid, will not become invalid over the life time of a guest. However, operations like the resetting of all event channels may involve decreasing one of the bounds checked when determining validity. This may lead to bug checks triggering, crashing the host. An unprivileged guest may be able to crash Xen, leading to a Denial of Service (DoS) for the entire system. All Xen versions from 4.4 onwards are vulnerable. Xen versions 4.3 and earlier are not vulnerable. Only systems with untrusted guests permitted to create more than the default number of event channels are vulnerable. This number depends on the architecture and type of guest. For 32-bit x86 PV guests, this is 1023; for 64-bit x86 PV guests, and for all ARM guests, this number is 4095. Systems where untrusted guests are limited to fewer than this number are not vulnerable. Note that xl and libxl limit max_event_channels to 1023 by default, so systems using exclusively xl, libvirt+libxl, or their own toolstack based on libxl, and not explicitly setting max_event_channels, are not vulnerable.

A vulnerability was found in Linux kernel where non-blocking socket in llcp_sock_connect() leads to leak and eventually hanging-up the system.

In the Linux kernel before 4.20.14, expand_downwards in mm/mmap.c lacks a check for the mmap minimum address, which makes it easier for attackers to exploit kernel NULL pointer dereferences on non-SMAP platforms. This is related to a capability check for the wrong task.

An issue was discovered in sd-bus in systemd 239. bus_process_object() in libsystemd/sd-bus/bus-objects.c allocates a variable-length stack buffer for temporarily storing the object path of incoming D-Bus messages. An unprivileged local user can exploit this by sending a specially crafted message to PID1, causing the stack pointer to jump over the stack guard pages into an unmapped memory region and trigger a denial of service (systemd PID1 crash and kernel panic).

A flaw was found in the Linux kernel's vfio interface implementation that permits violation of the user's locked memory limit. If a device is bound to a vfio driver, such as vfio-pci, and the local attacker is administratively granted ownership of the device, it may cause a system memory exhaustion and thus a denial of service (DoS). Versions 3.10, 4.14 and 4.18 are vulnerable.

An issue was discovered in can_can_gw_rcv in net/can/gw.c in the Linux kernel through 4.19.13. The CAN frame modification rules allow bitwise logical operations that can be also applied to the can_dlc field. The privileged user "root" with CAP_NET_ADMIN can create a CAN frame modification rule that makes the data length code a higher value than the available CAN frame data size. In combination with a configured checksum calculation where the result is stored relatively to the end of the data (e.g. cgw_csum_xor_rel) the tail of the skb (e.g. frag_list pointer in skb_shared_info) can be rewritten which finally can cause a system crash. Because of a missing check, the CAN drivers may write arbitrary content beyond the data registers in the CAN controller's I/O memory when processing can-gw manipulated outgoing frames.

The mem_cgroup_usage_unregister_event function in mm/memcontrol.c in the Linux kernel before 3.2.10 does not properly handle multiple events that are attached to the same eventfd, which allows local users to cause a denial of service (NULL pointer dereference and system crash) or possibly have unspecified other impact by registering memory threshold events.

A flaw was found in the Linux kernel in the function hid_debug_events_read() in drivers/hid/hid-debug.c file which may enter an infinite loop with certain parameters passed from a userspace. A local privileged user ("root") can cause a system lock up and a denial of service. Versions from v4.18 and newer are vulnerable.

In the Linux kernel before 5.1, there is a memory leak in __feat_register_sp() in net/dccp/feat.c, which may cause denial of service, aka CID-1d3ff0950e2b.

A memory leak in the i2400m_op_rfkill_sw_toggle() function in drivers/net/wimax/i2400m/op-rfkill.c in the Linux kernel before 5.3.11 allows attackers to cause a denial of service (memory consumption), aka CID-6f3ef5c25cc7.

Two memory leaks in the rtl_usb_probe() function in drivers/net/wireless/realtek/rtlwifi/usb.c in the Linux kernel through 5.3.11 allow attackers to cause a denial of service (memory consumption), aka CID-3f9361695113.

An issue was discovered in Xen through 4.12.x allowing 32-bit Arm guest OS users to cause a denial of service (out-of-bounds access) because certain bit iteration is mishandled. In a number of places bitmaps are being used by the hypervisor to track certain state. Iteration over all bits involves functions which may misbehave in certain corner cases: On 32-bit Arm accesses to bitmaps with bit a count which is a multiple of 32, an out of bounds access may occur. A malicious guest may cause a hypervisor crash or hang, resulting in a Denial of Service (DoS). All versions of Xen are vulnerable. 32-bit Arm systems are vulnerable. 64-bit Arm systems are not vulnerable.

A memory leak in the i40e_setup_macvlans() function in drivers/net/ethernet/intel/i40e/i40e_main.c in the Linux kernel through 5.3.11 allows attackers to cause a denial of service (memory consumption) by triggering i40e_setup_channel() failures, aka CID-27d461333459.

An issue was discovered in Xen through 4.12.x allowing x86 guest OS users to cause a denial of service (infinite loop) because certain bit iteration is mishandled. In a number of places bitmaps are being used by the hypervisor to track certain state. Iteration over all bits involves functions which may misbehave in certain corner cases: On x86 accesses to bitmaps with a compile time known size of 64 may incur undefined behavior, which may in particular result in infinite loops. A malicious guest may cause a hypervisor crash or hang, resulting in a Denial of Service (DoS). All versions of Xen are vulnerable. x86 systems with 64 or more nodes are vulnerable (there might not be any such systems that Xen would run on). x86 systems with less than 64 nodes are not vulnerable.

When GNOME Dia before 2019-11-27 is launched with a filename argument that is not a valid codepoint in the current encoding, it enters an endless loop, thus endlessly writing text to stdout. If this launch is from a thumbnailer service, this output will usually be written to disk via the system's logging facility (potentially with elevated privileges), thus filling up the disk and eventually rendering the system unusable. (The filename can be for a nonexistent file.) NOTE: this does not affect an upstream release, but affects certain Linux distribution packages with version numbers such as 0.97.3.

relay_open in kernel/relay.c in the Linux kernel through 5.4.1 allows local users to cause a denial of service (such as relay blockage) by triggering a NULL alloc_percpu result.

A memory leak in the af9005_identify_state() function in drivers/media/usb/dvb-usb/af9005.c in the Linux kernel through 5.3.9 allows attackers to cause a denial of service (memory consumption), aka CID-2289adbfa559.

A memory leak in the predicate_parse() function in kernel/trace/trace_events_filter.c in the Linux kernel through 5.3.11 allows attackers to cause a denial of service (memory consumption), aka CID-96c5c6e6a5b6.

A memory leak in the sof_set_get_large_ctrl_data() function in sound/soc/sof/ipc.c in the Linux kernel through 5.3.9 allows attackers to cause a denial of service (memory consumption) by triggering sof_get_ctrl_copy_params() failures, aka CID-45c1380358b1.

A memory leak in the nl80211_get_ftm_responder_stats() function in net/wireless/nl80211.c in the Linux kernel through 5.3.11 allows attackers to cause a denial of service (memory consumption) by triggering nl80211hdr_put() failures, aka CID-1399c59fa929. NOTE: third parties dispute the relevance of this because it occurs on a code path where a successful allocation has already occurred

A memory leak in the rtl8xxxu_submit_int_urb() function in drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c in the Linux kernel through 5.3.11 allows attackers to cause a denial of service (memory consumption) by triggering usb_submit_urb() failures, aka CID-a2cdd07488e6.

An issue was discovered in Xen through 4.12.x allowing Arm domU attackers to cause a denial of service (infinite loop) involving a LoadExcl or StoreExcl operation.

An issue was discovered in Xen 4.8.x through 4.11.x allowing x86 PV guest OS users to cause a denial of service because mishandling of failed IOMMU operations causes a bug check during the cleanup of a crashed guest.

An issue was discovered in Xen through 4.11.x allowing x86 PV guest OS users to cause a denial of service because of an incompatibility between Process Context Identifiers (PCID) and shadow-pagetable switching.

An issue was discovered in Xen through 4.11.x allowing x86 PV guest OS users to cause a denial of service by leveraging a long-running operation that exists to support restartability of PTE updates.

An issue was discovered in Xen through 4.12.x allowing Arm domU attackers to cause a denial of service (infinite loop) involving a compare-and-exchange operation.

An issue was discovered in drivers/xen/balloon.c in the Linux kernel before 5.2.3, as used in Xen through 4.12.x, allowing guest OS users to cause a denial of service because of unrestricted resource consumption during the mapping of guest memory, aka CID-6ef36ab967c7.

An issue was discovered in the Linux kernel before 5.0.19. There is an out-of-bounds array access in __xfrm_policy_unlink, which will cause denial of service, because verify_newpolicy_info in net/xfrm/xfrm_user.c mishandles directory validation.

An out-of-bounds memory access flaw was found in the ATI VGA device emulation of QEMU. This flaw occurs in the ati_2d_blt() routine while handling MMIO write operations when the guest provides invalid values for the destination display parameters. A malicious guest could use this flaw to crash the QEMU process on the host, resulting in a denial of service.

An issue was discovered in the Linux kernel before 5.2.3. There is a NULL pointer dereference caused by a malicious USB device in the drivers/media/usb/zr364xx/zr364xx.c driver.

An issue was discovered in the Linux kernel before 5.1.8. There is a NULL pointer dereference caused by a malicious USB device in the drivers/media/usb/siano/smsusb.c driver.

An issue was discovered in the Linux kernel before 5.0.14. There is a NULL pointer dereference caused by a malicious USB device in the drivers/usb/misc/yurex.c driver.

An issue was discovered in the Linux kernel before 5.1.8. There is a NULL pointer dereference caused by a malicious USB device in the drivers/usb/misc/sisusbvga/sisusb.c driver.

The I/O implementation for block devices in the Linux kernel before 2.6.33 does not properly handle the CLONE_IO feature, which allows local users to cause a denial of service (I/O instability) by starting multiple processes that share an I/O context.

drivers/net/wireless/ath/ath6kl/usb.c in the Linux kernel through 5.2.9 has a NULL pointer dereference via an incomplete address in an endpoint descriptor.

check_input_term in sound/usb/mixer.c in the Linux kernel through 5.2.9 mishandles recursion, leading to kernel stack exhaustion.

An issue was discovered in the Linux kernel before 5.1.8. There is a double-free caused by a malicious USB device in the drivers/usb/misc/rio500.c driver.

An issue was discovered in the Linux kernel before 5.1.17. There is a NULL pointer dereference caused by a malicious USB device in the sound/usb/line6/pcm.c driver.

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.

The ahci_commit_buf function in ide/ahci.c in QEMU allows attackers to cause a denial of service (NULL dereference) when the command header 'ad->cur_cmd' is null.

P2M pool freeing may take excessively long The P2M pool backing second level address translation for guests may be of significant size. Therefore its freeing may take more time than is reasonable without intermediate preemption checks. Such checking for the need to preempt was so far missing.

Recent x86 CPUs offer functionality named Control-flow Enforcement Technology (CET). A sub-feature of this are Shadow Stacks (CET-SS). CET-SS is a hardware feature designed to protect against Return Oriented Programming attacks. When enabled, traditional stacks holding both data and return addresses are accompanied by so called "shadow stacks", holding little more than return addresses. Shadow stacks aren't writable by normal instructions, and upon function returns their contents are used to check for possible manipulation of a return address coming from the traditional stack. In particular certain memory accesses need intercepting by Xen. In various cases the necessary emulation involves kind of replaying of the instruction. Such replaying typically involves filling and then invoking of a stub. Such a replayed instruction may raise an exceptions, which is expected and dealt with accordingly. Unfortunately the interaction of both of the above wasn't right: Recovery involves removal of a call frame from the (traditional) stack. The counterpart of this operation for the shadow stack was missing.

drivers/firmware/dell_rbu.c in the Linux kernel before 2.6.27.13, and 2.6.28.x before 2.6.28.2, allows local users to cause a denial of service (system crash) via a read system call that specifies zero bytes from the (1) image_type or (2) packet_size file in /sys/devices/platform/dell_rbu/.

fs/splice.c in the splice subsystem in the Linux kernel before 2.6.22.2 does not properly handle a failure of the add_to_page_cache_lru function, and subsequently attempts to unlock a page that was not locked, which allows local users to cause a denial of service (kernel BUG and system crash), as demonstrated by the fio I/O tool.

A flaw was found in the Linux kernel. A corrupted timer tree caused the task wakeup to be missing in the timerqueue_add function in lib/timerqueue.c. This flaw allows a local attacker with special user privileges to cause a denial of service, slowing and eventually stopping the system while running OSP.

An issue was discovered in Xen 4.8.x through 4.10.x allowing x86 PVH guest OS users to cause a denial of service (NULL pointer dereference and hypervisor crash) by leveraging the mishandling of configurations that lack a Local APIC.