skb drops due to the usage of pfmemalloc reserves were difficult to debug.
Additional diagnostics was introduced to make it easier to detect and analyze skb drops due to the usage of pfmemalloc reserves.
KVM did not update CPUID bits OSXSAVE and OSPKE in some cases.
It was discovered that CPUID bits OSXSAVE and OSPKE were not updated properly by KVM when the guest system rebooted. As a result, the guest system could crash.
The per-container limit on the network interfaces was too low for Docker in some cases.
It was discovered that Docker running inside a Virtuozzo container could hit the limit on the network interfaces (256) when it tried to start 50+ its containers. This fix allows changing that limit for the running containers and increases the default limit to 1024.
txqueuelen could not be changed via SIOCSIFTXQLEN ioctl on the host.
Kernel crash in ext4_clear_inode().
A large tarball with a lot of small files can fail to unpack inside a container if kmem limit is set.
It was found that unpacking a large tarball with a lot of small files could fail inside a container. This could happen because kmem limit was hit prematurely, while reclaimable memory was still available.
sr_mod: kernel crash in sr_block_revalidate_disk().
overlayfs: kernel crash in may_open().
CVE-2019-10140. An attacker with local access can create a denial of service situation via NULL pointer dereference in ovl_posix_acl_create(). The ovl_create() function can return a positive number leading to a null pointer derference of path in may_open(). This can allow attackers with ability to create directories on overlayfs to crash the kernel creating a Denial Of Service (DOS).
Links to certain files in /proc/ inside containers were not validated.
It was discovered that a malicious user inside a Virtuozzo container could potentially overwrite "vzctl" binary on the host. The attacker could replace executables in that container with symlinks to /proc/self/exe. After that, "vzctl exec" called from the host to run one of such executables would try to run the host's "vzctl" there instead. If the attacker managed to intercept that, they would be able to change the contents of the host's "vzctl" binary. The issue is similar to CVE-2019-5736, but affects "vzctl" rather than "runc".
Kernel crash (BUG_ON) ploop_relocblks_ioc().
/proc/sys/net/core/somaxconn was not available in the containers.
userfaultfd bypasses tmpfs file permissions.
A flaw was found in the implementation of userfaultfd. An attacker is able to bypass file permissions on filesystems mounted with tmpfs/hugetlbs to modify a file and possibly disrupt normal system behaviour. At this time there is an understanding there is no crash or priviledge escalation but the impact of modifications on these filesystems of files in production systems may have adverse affects.
ipvs: an unneeded debug message is output when a network namespace is initialized.
Debug message 'IPVS: Creating netns size=... id=...' could be output many times to the system log when the network namespaces are initialized, making the log less readable.
'perf record -a' causes segfaults in applications executing vsyscalls.
Some operations with ebtables could consume large amounts of memory, resulting in DoS.
A flaw was found in the implementation of ebtables in the Linux kernel. A local attacker in a container could exploit it to consume large amounts of memory, eventually causing denial of service on the host.
Kernel crash (access out of bounds) in SyS_mincore().
(enhancement) FUSE: backported immediate-write support for the fast path.