A flaw was found in Linux kernel's KVM virtualization subsystem. The VMX code does not restore the GDT.LIMIT to the previous host value, but instead sets it to 64KB. With a corrupted GDT limit a host's userspace code has an ability to place malicious entries in the GDT, particularly to the per-cpu variables. An attacker can use this to escalate their privileges.

Linux kernel is vulnerable to a stack-out-of-bounds write in the ext4 filesystem code when mounting and writing to a crafted ext4 image in ext4_update_inline_data(). An attacker could use this to cause a system crash and a denial of service.

It was discovered in the Linux kernel before 4.11-rc8 that root can gain direct access to an internal keyring, such as '.dns_resolver' in RHEL-7 or '.builtin_trusted_keys' upstream, by joining it as its session keyring. This allows root to bypass module signature verification by adding a new public key of its own devising to the keyring.

The inode_init_owner function in fs/inode.c in the Linux kernel through 3.16 allows local users to create files with an unintended group ownership, in a scenario where a directory is SGID to a certain group and is writable by a user who is not a member of that group. Here, the non-member can trigger creation of a plain file whose group ownership is that group. The intended behavior was that the non-member can trigger creation of a directory (but not a plain file) whose group ownership is that group. The non-member can escalate privileges by making the plain file executable and SGID.

An issue was discovered in fs/f2fs/super.c in the Linux kernel through 4.17.3, which does not properly validate secs_per_zone in a corrupted f2fs image, as demonstrated by a divide-by-zero error.

An issue was discovered in fs/f2fs/inline.c in the Linux kernel through 4.4. A denial of service (out-of-bounds memory access and BUG) can occur for a modified f2fs filesystem image in which an inline inode contains an invalid reserved blkaddr.

An issue was discovered in fs/f2fs/inode.c in the Linux kernel through 4.17.3. A denial of service (slab out-of-bounds read and BUG) can occur for a modified f2fs filesystem image in which FI_EXTRA_ATTR is set in an inode.

An issue was discovered in fs/f2fs/super.c in the Linux kernel through 4.17.3. There is an out-of-bounds read or a divide-by-zero error for an incorrect user_block_count in a corrupted f2fs image, leading to a denial of service (BUG).

An issue was discovered in fs/f2fs/super.c in the Linux kernel through 4.14. A denial of service (out-of-bounds memory access and BUG) can occur upon encountering an abnormal bitmap size when mounting a crafted f2fs image.

An issue was discovered in fs/xfs/libxfs/xfs_inode_buf.c in the Linux kernel through 4.17.3. A denial of service (memory corruption and BUG) can occur for a corrupted xfs image upon encountering an inode that is in extent format, but has more extents than fit in the inode fork.

An issue was discovered in fs/xfs/libxfs/xfs_attr_leaf.c in the Linux kernel through 4.17.3. An OOPS may occur for a corrupted xfs image after xfs_da_shrink_inode() is called with a NULL bp.

An issue was discovered in fs/xfs/xfs_icache.c in the Linux kernel through 4.17.3. There is a NULL pointer dereference and panic in lookup_slow() on a NULL inode->i_ops pointer when doing pathwalks on a corrupted xfs image. This occurs because of a lack of proper validation that cached inodes are free during allocation.

An issue was discovered in the Linux kernel through 4.17.3. An Integer Overflow in kernel/time/posix-timers.c in the POSIX timer code is caused by the way the overrun accounting works. Depending on interval and expiry time values, the overrun can be larger than INT_MAX, but the accounting is int based. This basically makes the accounting values, which are visible to user space via timer_getoverrun(2) and siginfo::si_overrun, random. For example, a local user can cause a denial of service (signed integer overflow) via crafted mmap, futex, timer_create, and timer_settime system calls.

The alarm_timer_nsleep function in kernel/time/alarmtimer.c in the Linux kernel through 4.17.3 has an integer overflow via a large relative timeout because ktime_add_safe is not used.

In arch/x86/kvm/vmx.c in the Linux kernel before 4.17.2, when nested virtualization is used, local attackers could cause L1 KVM guests to VMEXIT, potentially allowing privilege escalations and denial of service attacks due to lack of checking of CPL.

An issue was discovered in the Linux kernel through 4.17.2. vbg_misc_device_ioctl() in drivers/virt/vboxguest/vboxguest_linux.c reads the same user data twice with copy_from_user. The header part of the user data is double-fetched, and a malicious user thread can tamper with the critical variables (hdr.size_in and hdr.size_out) in the header between the two fetches because of a race condition, leading to severe kernel errors, such as buffer over-accesses. This bug can cause a local denial of service and information leakage.

An issue was discovered in the Linux kernel through 4.17.2. Since the page allocator does not yield CPU resources to the owner of the oom_lock mutex, a local unprivileged user can trivially lock up the system forever by wasting CPU resources from the page allocator (e.g., via concurrent page fault events) when the global OOM killer is invoked. NOTE: the software maintainer has not accepted certain proposed patches, in part because of a viewpoint that "the underlying problem is non-trivial to handle.

A flaw was found affecting the Linux kernel before version 4.17. By mmap()ing a FUSE-backed file onto a process's memory containing command line arguments (or environment strings), an attacker can cause utilities from psutils or procps (such as ps, w) or any other program which makes a read() call to the /proc/<pid>/cmdline (or /proc/<pid>/environ) files to block indefinitely (denial of service) or for some controlled time (as a synchronization primitive for other attacks).

In the Linux Kernel before version 4.16.11, 4.14.43, 4.9.102, and 4.4.133, multiple race condition errors when handling probe, disconnect, and rebind operations can be exploited to trigger a use-after-free condition or a NULL pointer dereference by sending multiple USB over IP packets.

In the Linux Kernel before version 4.15.8, 4.14.25, 4.9.87, 4.4.121, 4.1.51, and 3.2.102, an error in the "_sctp_make_chunk()" function (net/sctp/sm_make_chunk.c) when handling SCTP packets length can be exploited to cause a kernel crash.