ptrace: incorrect error handling leads to corruption and DoS.
The implementation of ptrace in the kernel does not handle errors correctly when working with the debug registers. As a result, the hardware breakpoints could become corrupted. An unprivileged user could exploit this flaw to crash the kernel resulting in a denial-of-service, or, potentially, to escalate their privileges in the system.
KVM: error in exception handling leads to wrong debug stack.
A flaw was found in how KVM handled exceptions delivered after Mov SS or Pop SS instructions have encountered a breakpoint. As a result, exceptions passed to the guest kernel could have wrong values on the stack. An unprivileged KVM guest user could use this flaw to crash the guest kernel or, potentially, escalate their privileges in the guest system.
ip utility hangs in netlink_recvmsg().
It was discovered that the newer versions of ip utility (4.11.0, for example) may hang in netlink_recvmsg() when running on the kernel 3.10.0-693.21.1.vz7.46.7 and older. This was caused by mis-interpretation of netlink commands.
Missing permissions check for request_key() destination allows local attackers to add keys to keyring without write permission.
The KEYS subsystem omitted an access-control check when writing a key to the default keyring of the current task, allowing a local user to bypass security checks for the keyring. This compromised the validity of the keyring for those who relied on it.
System-wide OS fingerprint list was accessible to unprivileged users.
It was discovered that xt_osf_fingers data structure was accessible from any network namespace. This allowed unprivileged local users to bypass intended access restrictions and modify the system-wide OS fingerprint list used by specific iptables rules.
Netlink monitor created in a namespace could observe system-wide activity.
It was discovered that a nlmon link inside a child network namespace was not restricted to that namespace. An unprivilged local user could exploit that to monitor system-wide netlink activity.
Potential unprivileged access to the kernel structures used by netfilter conntrack helpers.
It was discovered that nfnl_cthelper_list structure was accessible to any user with CAP_NET_ADMIN capability in a network namespace. An unprivilged local user could exploit that to affect netfilter conntrack helpers on the host.
Kernel crash in move_freepages() due to incorrect BUG_ON() check.
It was discovered that the BUG_ON() check in move_freepages() did not verify that the relevant memory pages were valid. The kernel could crash as a result.
Kernel crash (stack overflow) caused by lots of internal mounts.
It was discovered that clone_mnt() did not clear MNT_INTERNAL flag for the internal mounts. As a result, the kernel could crash due to a stack overflow if lots of bind mounts of /proc/*/ns/* were created in a new namespace.
Kernel crash in dccp_write_xmit().
If "dccp_ipv6" module was loaded on the host, a local unprivileged user could trigger a kernel crash in dccp_write_xmit() or inet_csk_get_port() using a specially crafted sequence of system calls.
Kernel crash in ip6mr_sk_done().
If the kernel failed to create an IPv6 socket, for example, due to cgroup.memsw limit, it would crash in ip6mr_sk_done() when trying to clean up multicast routes.
IPv6 routing tables incorrectly handled routing rules for throw routes.
It was discovered that IPv6 routing tables incorrectly handled routing rules for throw routes. This happened because errors were not propagated properly up to the fib_rules_lookup().
Container remained mounted in some cases after 'shutdown -h now' in it.
It was discovered that incorrect state of a container could be reported in /sys/fs/cgroup/ve/CTID/ve.state in some cases, which confused the user-space tools. As a result, a container could remain mounted after 'shutdown -h now' in it.
ebtables: out-of-bounds write via userland offsets in ebt_entry struct.
It was discovered that the implementation of ebtables in the kernel did not properly validate the offsets received from the user space. A local user with enough privileges in the user and network namespaces could use that to trigger an out-of-bounds write to the kernel address space.
Potential kernel hang (lockup) during destruction of cgroups.
'memory' and 'memsw' counters could be overcharged when the limit of 'kmem' counter was reached. This would result in a kernel lockup during destruction of cgroups.
Potential kernel hang (endless loop) in try_charge().
Ploop: some IO requests were not marked as completed in case of errors.
High cpu usage in isolate_freepages_block().
vstorage-mount spent a lot of time in isolate_freepages_block() in some cases, causing performance issues.
Memcg swpin/swpout stats were calculated incorrectly.
Memory cgroups were not released when starting/stopping a container with Docker.
Memory cgroups were not correctly released during start/stop of a container with Docker. If the node had a significant amount of containers with Docker, this could lead to stopped containers not starting again.
Hard lockups happened when the kernel was processing SAK (Secure Attention Key).
Docker v17.11 and newer failed to start in a container.
Starting from v17.11, Docker checks is all cgroups are mounted and refuses to start if some cgroups are not. Some of Virtuozzo-specific cgroups were visible in the containers and were not mounted there, which prevented Docker from starting properly.
Kernel crash in mem_cgroup_iter().
Potential denial of service due to extensive memory consumption.
It was discovered that some operations with files in a container could lead to denial of service on the host due to extensive memory consumption.
loop: potential data race between open() and release() leading to use-after-free.
It was found that release() operation for the loop devices has insufficient protection for the device structures against the accesses from the concurrent open() operations. A local attacker can use specially arranged concurrent operations with a loop device to cause a denial of service (kernel crash due to a use-after-free error).
netfilter: Use-after-free in tcpmss_mangle_packet().
If the system uses iptables and there are iptables rules with TCPMSS action there, a remote attacker may cause a denial of service (use-after-free in tcpmss_mangle_packet function leading to memory corruption) or possibly have unspecified other impact by sending specially crafted network packets.