Denial of service by corrupting mountpoint reference counter.
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).
ext4: use-after-free when unmounting a corrupted file system with files that have no links.
futex: potential system hang due to a missing unlock operation in the error path of futex_wait_requeue_pi().
cbt: potential endless loops in the error paths.
netfilter: potential memory corruption caused by a helper from nf_conntrack_h323 module.
CVE-2020-14305 was later assigned to this issue. See also: https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2020-14305
nf_conntrack: potential kernel crash in netlink_has_listeners().
qxl: kernel crash in qxl_release_fence_buffer_objects().
Use-after-free read in napi_gro_frags().
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.
i40iw: kernel complains about failed RTNL assertion in i40iw_addr_resolve_neigh().
nfsd: memory corruption in nfsd4_lock().
netfilter: kernel crash in the implementation of nf_tables due to use-after-free in dynamic operations.
A container with NFS server could force other such containers to use the older NFSv4 client tracker, which slows down NFS mounts.
mpt2sas: scheduling while atomic in _scsih_io_done().
ext4: a race between online resizing and write operations could lead to kernel crashes or data corruption.
Potential leak of a reference counter for a memory cgroup in memcg_expand_shrinker_maps().
Potential corruption of ploop images due to a race between the truncation thread and resize operations.
xfs: potential denial of service caused by missing unlock operation in xfs_setattr_nonsize().
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.
nf_tables: kernel crash in nft_rbtree_lookup().
Kernel crash due to out-of-bounds memory accesses in process_vm_readv().
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.
scsi: printing lots of messages about rejected I/O causes a hard lockup and a kernel crash.
Potential kernel crash in __radix_tree_insert() when fscache is used for NFS mounts.
sunrpc: potential kernel crash in bc_svc_process().
Kernel crash in the implementation of epoll_ctl system call.
Kernel crash in __generic_splice_read().
KVM: Out-of-bounds memory access via MMIO ring buffer.
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.
Potential kernel crash in __tcp_retransmit_skb().
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.
Certain operations with iptables in a container may crash the kernel.
A container that tries to mount NFS shares may cause the whole system to hang in certain conditions.
tun: potential kernel crash when TUNSETIFF ioctl operation is used for a device with an invalid name.
Use-after-free in __blk_drain_queue() function.
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.
sunrpc: kernel crash in svcauth_unix_set_client().
Data corruption in the EXT4 file system when truncating the extent index blocks.
Kernel complained about busy inodes after unmount of NFS shares and crashed in certain cases.
memcg: race condition between reparenting and kmem uncharging.
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.
Kernel crashed in down_read() when a FUSE file system was exported via NFS.
vhost-net: guest to host kernel escape during migration
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.
infiniband: use-after-free in ucma_leave_multicast().
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.
megaraid_sas: potential kernel crash due to a NULL pointer dereference in megasas_free_cmds().
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.
Page cache side channel attacks via mincore().
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.
The warning in mem_cgroup_reparent_charges() was triggered too early and too often in certain cases.
kvm: potential system hang due to an error in mmu_shrink_scan().
nfs: NULL pointer dereference due to an anomalized NFS message sequence.
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.
fuse_kio_pcs: kernel crash in pcs_sockio_xmit().
Processes could get stuck in copy_net_ns() forever.
vziolimit: kernel crash due to a division by zero in throttle_charge().
mem_cgroup_reparent_charges() could get stuck while holding cgroup_mutex and make the whole system hang.
Kernel crash in memcg_inc_ws_activate().
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().
kvm: inefficient memory shrinking for VMs.
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.
fuse_kio_pcs: latency was calculated incorrectly.
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.
tcp: integer overflow while processing SACK blocks allows remote denial of service.
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.
Processes could hang while closing a file located on the storage cluster.
OOM killer would kill tasks from cgroups without memory guarantees first.
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.
ploop: kernel crash in ploop_congested().
ext4: inode tables created during online resize were not zeroed.
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.
Windows Server 2016 Essentials failed to install into a QEMU VM with disabled PMU.
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.
ploop: 'pcompact' could hang if run simultaneously with 'ploop-balloon status'
Memory leak in the implementation of IPv4 routing.
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.
Kernel crash in memcg_css_release_check_kmem().
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().
I/O errors were reported after a successful replacement of the ploop images.
'ploop replace' did not clear 'abort' flag.
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.