CVE-2018-1095

The ext4_xattr_check_entries function in fs/ext4/xattr.c in the Linux kernel through 4.15.15 does not properly validate xattr sizes, which causes misinterpretation of a size as an error code, and consequently allows attackers to cause a denial of service (get_acl NULL pointer dereference and system crash) via a crafted ext4 image.

This kernel update is based on the upstream 4.14.40 and fixes at least the following security issues:

On x86, MOV SS and POP SS behave strangely if they encounter a data breakpoint. If this occurs in a KVM guest, KVM incorrectly thinks that a #DB instruction was caused by the undocumented ICEBP instruction. This results in #DB being delivered to the guest kernel with an incorrect RIP on the stack. On most guest kernels, this will allow a guest user to DoS the guest kernel or even to escalate privilege to that of the guest kernel (CVE-2018-1087).

The ext4_iget function in fs/ext4/inode.c in the Linux kernel through 4.15.15 mishandles the case of a root directory with a zero i_links_count, which allows attackers to cause a denial of service (ext4_process_freed_data NULL pointer dereference and OOPS) via a crafted ext4 image (CVE-2018-1092).

The ext4_valid_block_bitmap function in fs/ext4/balloc.c in the Linux kernel through 4.15.15 allows attackers to cause a denial of service (out-of-bounds read and system crash) via a crafted ext4 image because balloc.c and ialloc.c do not validate bitmap block numbers (CVE-2018-1093).

The ext4_fill_super function in fs/ext4/super.c in the Linux kernel through 4.15.15 does not always initialize the crc32c checksum driver, which allows attackers to cause a denial of service (ext4_xattr_inode_hash NULL pointer dereference and system crash) via a crafted ext4 image (CVE-2018-1094).

The ext4_xattr_check_entries function in fs/ext4/xattr.c in the Linux kernel through 4.15.15 does not properly validate xattr sizes, which causes misinterpretation of a size as an error code, and consequently allows attackers to cause a denial of service (get_acl NULL pointer dereference and system crash) via a crafted ext4 image (CVE-2018-1095).

Predictable Random Number Generator Weakness (CVE-2018-1108).

A null pointer dereference in dccp_write_xmit() function in net/dccp/output.c in the Linux kernel before v4.16-rc7 allows a local user to cause a denial of service by a number of certain crafted system calls (CVE-2018-1130).

The Linux kernel does not properly handle debug exceptions delivered after a stack switch operation via mov SS or pop SS instructions. During the stack switch operation, the exceptions are deferred. As a result, a local user can cause the kernel to crash (CVE-2018-8897).

WireGuard has been updated to 0.0.20180420.

For other fixes in this update, see the referenced changelogs.

This kernel-tmb update is based on the upstream 4.14.44 and fixes at least the following security issues:

This update adds KPTI mitigation for Meltdown (CVE-2017-5754) on 32bit x86.

The netfilter subsystem in the Linux kernel through 4.15.7 mishandles the case of a rule blob that contains a jump but lacks a user-defined chain, which allows local users to cause a denial of service (NULL pointer dereference) by leveraging the CAP_NET_RAW or CAP_NET_ADMIN capability, related to arpt_do_table in net/ipv4/netfilter/arp_tables.c, ipt_do_table in net/ipv4/netfilter/ip_tables.c, and ip6t_do_table in net/ipv6/netfilter/ip6_tables.c (CVE-2018-1065).

A flaw was found in the Linux kernel implementation of 32 bit syscall interface for bridging allowing a privileged user to arbitrarily write to a limited range of kernel memory. This flaw can be exploited not only by a system's privileged user (a real "root" user), but also by an attacker who is a privileged user (a "root" user) in a user+network namespace (CVE-2018-1068).

On x86, MOV SS and POP SS behave strangely if they encounter a data breakpoint. If this occurs in a KVM guest, KVM incorrectly thinks that a #DB instruction was caused by the undocumented ICEBP instruction. This results in #DB being delivered to the guest kernel with an incorrect RIP on the stack. On most guest kernels, this will allow a guest user to DoS the guest kernel or even to escalate privilege to that of the guest kernel (CVE-2018-1087).

The ext4_iget function in fs/ext4/inode.c in the Linux kernel through 4.15.15 mishandles the case of a root directory with a zero i_links_count, which allows attackers to cause a denial of service (ext4_process_freed_data NULL pointer dereference and OOPS) via a crafted ext4 image (CVE-2018-1092).

The ext4_valid_block_bitmap function in fs/ext4/balloc.c in the Linux kernel through 4.15.15 allows attackers to cause a denial of service (out-of-bounds read and system crash) via a crafted ext4 image because balloc.c and ialloc.c do not validate bitmap block numbers (CVE-2018-1093).

The ext4_fill_super function in fs/ext4/super.c in the Linux kernel through 4.15.15 does not always initialize the crc32c checksum driver, which allows attackers to cause a denial of service (ext4_xattr_inode_hash NULL pointer dereference and system crash) via a crafted ext4 image (CVE-2018-1094).

The ext4_xattr_check_entries function in fs/ext4/xattr.c in the Linux kernel through 4.15.15 does not properly validate xattr sizes, which causes misinterpretation of a size as an error code, and consequently allows attackers to cause a denial of service (get_acl NULL pointer dereference and system crash) via a crafted ext4 image (CVE-2018-1095).

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) (CVE-2018-1120).

A null pointer dereference in dccp_write_xmit() function in net/dccp/output.c in the Linux kernel before v4.16-rc7 allows a local user to cause a denial of service by a number of certain crafted system calls (CVE-2018-1130).

Speculative Store Bypass (SSB) – also known as Spectre Variant 4. Systems with microprocessors utilizing speculative execution and speculative execution of memory reads before the addresses of all prior memory writes are known may allow unauthorized disclosure of information to an attacker with local user access via a side-channel analysis (CVE-2018-3639). NOTE! This fix only apply to Amd hardware so far as Intel CPUs need a fixed microcode update in order for the fix to get activated. At the time of this release we dont yet know when Intel will release new microcode.

The Linux kernel does not properly handle debug…

This kernel-linus update is based on the upstream 4.14.44 and fixes at least the following security issues:

The netfilter subsystem in the Linux kernel through 4.15.7 mishandles the case of a rule blob that contains a jump but lacks a user-defined chain, which allows local users to cause a denial of service (NULL pointer dereference) by leveraging the CAP_NET_RAW or CAP_NET_ADMIN capability, related to arpt_do_table in net/ipv4/netfilter/arp_tables.c, ipt_do_table in net/ipv4/netfilter/ip_tables.c, and ip6t_do_table in net/ipv6/netfilter/ip6_tables.c (CVE-2018-1065).

A flaw was found in the Linux kernel implementation of 32 bit syscall interface for bridging allowing a privileged user to arbitrarily write to a limited range of kernel memory. This flaw can be exploited not only by a system's privileged user (a real "root" user), but also by an attacker who is a privileged user (a "root" user) in a user+network namespace (CVE-2018-1068).

On x86, MOV SS and POP SS behave strangely if they encounter a data breakpoint. If this occurs in a KVM guest, KVM incorrectly thinks that a #DB instruction was caused by the undocumented ICEBP instruction. This results in #DB being delivered to the guest kernel with an incorrect RIP on the stack. On most guest kernels, this will allow a guest user to DoS the guest kernel or even to escalate privilege to that of the guest kernel (CVE-2018-1087).

The ext4_iget function in fs/ext4/inode.c in the Linux kernel through 4.15.15 mishandles the case of a root directory with a zero i_links_count, which allows attackers to cause a denial of service (ext4_process_freed_data NULL pointer dereference and OOPS) via a crafted ext4 image (CVE-2018-1092).

The ext4_valid_block_bitmap function in fs/ext4/balloc.c in the Linux kernel through 4.15.15 allows attackers to cause a denial of service (out-of-bounds read and system crash) via a crafted ext4 image because balloc.c and ialloc.c do not validate bitmap block numbers (CVE-2018-1093).

The ext4_fill_super function in fs/ext4/super.c in the Linux kernel through 4.15.15 does not always initialize the crc32c checksum driver, which allows attackers to cause a denial of service (ext4_xattr_inode_hash NULL pointer dereference and system crash) via a crafted ext4 image (CVE-2018-1094).

The ext4_xattr_check_entries function in fs/ext4/xattr.c in the Linux kernel through 4.15.15 does not properly validate xattr sizes, which causes misinterpretation of a size as an error code, and consequently allows attackers to cause a denial of service (get_acl NULL pointer dereference and system crash) via a crafted ext4 image (CVE-2018-1095).

Predictable Random Number Generator Weakness (CVE-2018-1108).

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) (CVE-2018-1120).

A null pointer dereference in dccp_write_xmit() function in net/dccp/output.c in the Linux kernel before v4.16-rc7 allows a local user to cause a denial of service by a number of certain crafted system calls (CVE-2018-1130).

Speculative Store Bypass (SSB) – also known as Spectre Variant 4. Systems with microprocessors utilizing speculative execution and speculative execution of memory reads before the addresses of all prior memory writes are known may allow unauthorized disclosure of information to an attacker with local user access via a side-channel analysis (CVE-2018-3639). NOTE! This fix only apply to Amd hardware so far as Intel CPUs need a fixed microcode update in order for the fix to get activated. At the time of this release we dont yet know when Intel will release new microcode.

The Linux kernel does not properly handle debug exceptions…

Wen Xu discovered that the ext4 filesystem implementation in the Linux kernel did not properly initialize the crc32c checksum driver. A local attacker could use this to cause a denial of service (system crash). (CVE-2018-1094)

It was discovered that the cdrom driver in the Linux kernel contained an incorrect bounds check. A local attacker could use this to expose sensitive information (kernel memory). (CVE-2018-10940)

Wen Xu discovered that the ext4 file system implementation in the Linux kernel did not properly validate xattr sizes. A local attacker could use this to cause a denial of service (system crash). (CVE-2018-1095)

Jann Horn discovered that the 32 bit adjtimex() syscall implementation for 64 bit Linux kernels did not properly initialize memory returned to user space in some situations. A local attacker could use this to expose sensitive information (kernel memory). (CVE-2018-11508)

It was discovered that an information leak vulnerability existed in the floppy driver in the Linux kernel. A local attacker could use this to expose sensitive information (kernel memory). (CVE-2018-7755)

USN-3695-1 fixed vulnerabilities in the Linux kernel for Ubuntu 18.04 LTS. This update provides the corresponding updates for the Linux Hardware Enablement (HWE) kernel from Ubuntu 18.04 LTS for Ubuntu 16.04 LTS.

Wen Xu discovered that the ext4 file system implementation in the Linux kernel did not properly initialize the crc32c checksum driver. A local attacker could use this to cause a denial of service (system crash). (CVE-2018-1094)

It was discovered that the cdrom driver in the Linux kernel contained an incorrect bounds check. A local attacker could use this to expose sensitive information (kernel memory). (CVE-2018-10940)

Wen Xu discovered that the ext4 file system implementation in the Linux kernel did not properly validate xattr sizes. A local attacker could use this to cause a denial of service (system crash). (CVE-2018-1095)

Jann Horn discovered that the 32 bit adjtimex() syscall implementation for 64 bit Linux kernels did not properly initialize memory returned to user space in some situations. A local attacker could use this to expose sensitive information (kernel memory). (CVE-2018-11508)

It was discovered that an information leak vulnerability existed in the floppy driver in the Linux kernel. A local attacker could use this to expose sensitive information (kernel memory). (CVE-2018-7755)