readykernel-patch-85.17-116.0-1.vl7

It was discovered that a buffer overflow and memory corruption were possible if a system tried to mount an NFS v4 share where the files had security labels in the file attributes. An attacker would need to control the NFS server and make it send a specific series of responses to trigger the issue. The issue allows the attacker to crash the kernel on the client system or, potentially, escalate their privileges there.

It was discovered that a local attacker could pass a specially crafted configuration of conntrack to the kernel to cause a buffer overflow in ctnetlink_parse_tuple_filter() function. As a result, the kernel could crash.

A race condition was discovered in the implementation of usermode helpers in the kernel. An attacker could exploit it from a container to cause a denial-of-service (kernel crash due to a use-after-free), or, potentially, to escalate their privileges in the system.

It was discovered that the implementation of nf_tables did not properly validate certain parameters. An attacker could exploit this from a container to cause a kernel crash: NULL pointer dereference or a general protection fault in nf_tables_getset().

It was discovered that nfnetlink subsystem did not properly validate certain messages. An attacker could exploit this from a container to cause a kernel crash: skb_over_panic in skb_put().

It was discovered that use-after-free condition was possible in cdev_get() if multiple processes simultaneously accessed a character device in a certain way. A local attacker could potentially exploit this to crash the kernel.

It was found that if TPACKET_V3 was used and the kernel failed to obtain certain settings from a relevant network device, the retirement timer could be set incorrectly in the implementation AF_PACKET protocol. This could result in soft lockups and excessive CPU usage.

A NULL pointer dereference was found in the implementation of SELinux. The issue occurs while importing the Commercial IP Security Option (CIPSO) protocol category bitmap into SELinux extensible bitmap. Parsing of a specially crafted CIPSO packet sent by a remote attacker could lead to a kernel crash (remote DoS).

It was discovered that core dumps of userspace processes could contain copies of uninitialized kernel memory areas in certain cases. Although it is difficult for an attacker to control what data is in these areas, this issue, in theory, could be used to obtain sensitive information from the kernel.

An out-of-bounds read was found in the implementation of IPsec cryptographic algorithms ('authenc' module). When payload of a key was longer than 4 bytes but was not properly aligned, crypto_authenc_extractkeys() function could try to read data from a wrong location. This could lead to a kernel crash in crypto_ahash_setkey().

It was discovered that a race condition was possible between pivot_root() and put_mountpoint() operations. A local unprivileged attacker could exploit this to corrupt mountpoint reference counter and cause a denial of service (kernel crash).

See also: https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2020-14305.

A flaw was found in the implementation of GRO, which allows an attacker with local access to trigger a use-after-free read in napi_gro_frags() and, potentially, crash the system.

It was discovered that xfs_setattr_nonsize() would not unlock 'ILOCK' lock if the user or group were out of their disk quota. As a result, any subsequent operation, which needed to take 'ILOCK', would get stuck, leading to a denial of service.

It was discovered that the implementation of process_vm_readv() system call could try to access memory outside of the structures it was processing in certain cases. A local unprivileged user could use this vulnerability to crash the system.

An issue was found in the implementation of the coalesced MMIO write operation in KVM. The indices used to access an MMIO ring buffer could be supplied by a user-space process in the host system. An attacker with access to /dev/kvm could use this flaw to trigger out-of-bounds memory access and crash the host kernel or, potentially, escalate their privileges.

It was discovered that a local unprivileged attacker could use a specially crafted sequence of system calls to trigger either a kernel crash in __tcp_retransmit_skb() or use-after-free conditions, which could result in privilege escalation.

It was found that a use-after-free condition could be triggered in the block device subsystem while the outstanding command queue was drained. A patient local attacker can use this flaw to crash the system or, potentially, to escalate their privileges.

It was discovered that a race condition was possible between kmem uncharging and mem_cgroup_reparent_charges(). A kernel warning would be triggered as a result.

A buffer overflow vulnerability was found in the networking virtualization functionality (vhost-net) that could be abused during live migration of virtual machines. A privileged guest user may pass descriptors with invalid length to the host when live migration is underway to crash the host kernel or, potentially, escalate their privileges on the host.

It was found that ucma_leave_multicast() function from 'rdma_ucm' module could try to access a certain data structure after the structure had been freed. This allows an attacker to induce kernel memory corruption, leading to a system crash or other unspecified impact.

A flaw was found in 'megaraid_sas' kernel module. NULL pointer dereference can occur in megasas_free_cmds() function due incorrect error handling in megasas_alloc_cmds(). An attacker could exploit this to trigger a kernel crash.

It was discovered that a local attacker could exploit mincore() system call to obtain information about memory pages of the running applications from the page cache even if the contents of these memory pages were not available to the attacker.

An attacker, who is able to mount an exported NFS filesystem, is able to trigger a null pointer dereference by using an invalid NFS sequence. This can panic the machine and deny access to the NFS server. Any outstanding disk writes to the NFS server will be lost.

It was discovered that a race could happen between removal of memcg and workingset_refault() running in parallel. This could result in a kernel crash in memcg_inc_ws_activate().

It was discovered that a node with dozens of CPU cores, lots of RAM and many VMs running could get into a situation when almost all CPU cores were busy in mmu_shrink_scan(). This could happen because memory shrinking was done under kvm_lock spinlock and only for one VM at a time. All CPU cores but one just waited for kvm_lock in such cases, while the last one was busy with the actual memory shrinking for a VM.

It was found that the in-kernel implementation of Virtuozzo Storage client stored latency values in milliseconds rather than in microseconds, resulting in bogus statistics data.

An integer overflow was found in the way the Linux kernel's networking subsystem processed TCP Selective Acknowledgment (SACK) segments. While processing SACK segments, the Linux kernel's socket buffer (SKB) data structure becomes fragmented. Each fragment is about TCP maximum segment size (MSS) bytes. To efficiently process SACK blocks, the Linux kernel merges multiple fragmented SKBs into one, potentially overflowing the variable holding the number of segments. A remote attacker could use this flaw to crash the Linux kernel by sending a crafted sequence of SACK segments on a TCP connection with small value of TCP MSS, resulting in a denial of service.

If the amount of free memory is low, OOM killer would kill the tasks from cgroups without memory guarantees first. However, it seems more reasonable to kill the tasks from cgroups exceeding their guarantees the most.

It was discovered that inode tables created during online resize of an ext4 filesystem were not zeroed after that. This could potentially result in lower performance of the filesystem.

It was found that if no PMU counters were exposed to guest, KVM skipped the whole remaining PMU-related initialization, including filling of LBR-related data. As it turned out, Windows Server 2016 Essentials tried to access these data during the installation and failed to install as a result.

It was discovered that a certain sequence of operations related to IPv4 routing could trigger a kernel memory leak. An attacker could potentially exploit that from a container to cause a denial of service.

Freeing of a memory cgroup took longer than needed in certain cases.

It was found that the memcg ID number of a cgroup was released earlier than needed and could then be reused by a different cgroup. As a result, certain reference counters could be corrupted, leading to a kernel crash in memcg_css_release_check_kmem().

It was found that if a ploop image was revoked and then replaced using 'ploop replace', 'abort' flag was not cleared. As a result, subsequent I/O operations would fail.