RHSA-2017:2669 Important: kernel-rt security and bug fix update

Updated -

The kernel-rt packages contain the Linux kernel, the core of any Linux operating system.

Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE links.

This update also fixes multiple Moderate and Low impact security issues:

  • A flaw was found in the Linux kernel when attempting to "punch a hole" in files existing on an ext4 filesystem. When punching holes into a file races with the page fault of the same area, it is possible that freed blocks remain referenced from page cache pages mapped to process' address space. (CVE-2015-8839, Moderate)

  • It was found that when the gcc stack protector was enabled, reading the /proc/keys file could cause a panic in the Linux kernel due to stack corruption. This happened because an incorrect buffer size was used to hold a 64-bit timeout value rendered as weeks. (CVE-2016-7042, Moderate)

  • It was found that when file permissions were modified via chmod and the user modifying them was not in the owning group or capable of CAP_FSETID, the setgid bit would be cleared. Setting a POSIX ACL via setxattr sets the file permissions as well as the new ACL, but doesn't clear the setgid bit in a similar way. This could allow a local user to gain group privileges via certain setgid applications. (CVE-2016-7097, Moderate)

  • It was discovered that the Linux kernel since 3.6-rc1 with 'net.ipv4.tcp_fastopen' set to 1 can hit BUG() statement in tcp_collapse() function after making a number of certain syscalls leading to a possible system crash. (CVE-2016-8645, Moderate)

  • It was found that the blk_rq_map_user_iov() function in the Linux kernel's block device implementation did not properly restrict the type of iterator, which could allow a local attacker to read or write to arbitrary kernel memory locations or cause a denial of service (use-after-free) by leveraging write access to a /dev/sg device. (CVE-2016-9576, Moderate)

  • A double free vulnerability was found in netlink_dump, which could cause a denial of service or possibly other unspecified impact. Due to the nature of the flaw, privilege escalation cannot be fully ruled out, although we believe it is unlikely. (CVE-2016-9806, Moderate)

  • It was found that the fix for CVE-2016-9576 was incomplete: the Linux kernel's sg implementation did not properly restrict write operations in situations where the KERNEL_DS option is set. A local attacker to read or write to arbitrary kernel memory locations or cause a denial of service (use-after-free) by leveraging write access to a /dev/sg device. (CVE-2016-10088, Moderate)

  • A race condition leading to a NULL pointer dereference was found in the Linux kernel's Link Layer Control implementation. A local attacker with access to ping sockets could use this flaw to crash the system. (CVE-2017-2671, Moderate)

  • A vulnerability was found in the Linux kernel where having malicious IP options present would cause the ipv4_pktinfo_prepare() function to drop/free the dst. This could result in a system crash or possible privilege escalation. (CVE-2017-5970, Moderate)

  • It was found that the original fix for CVE-2016-6786 was incomplete. There exist a race between two concurrent sys_perf_event_open() calls when both try and move the same pre-existing software group into a hardware context. (CVE-2017-6001, Moderate)

  • The keyring_search_aux function in security/keys/keyring.c in the Linux kernel allows local users to cause a denial of service via a request_key system call for the "dead" key type. (CVE-2017-6951, Moderate)

  • The sg_ioctl function in drivers/scsi/sg.c in the Linux kernel allows local users to cause a denial of service (stack-based buffer overflow) or possibly have unspecified other impacts via a large command size in an SG_NEXT_CMD_LEN ioctl call, leading to out-of-bounds write access in the sg_write function. (CVE-2017-7187, Moderate)

  • The mm subsystem in the Linux kernel through 4.10.10 does not properly enforce the CONFIG_STRICT_DEVMEM protection mechanism, which allows local users to read or write to kernel memory locations in the first megabyte (and bypass slab-allocation access restrictions) via an application that opens the /dev/mem file, related to arch/x86/mm/init.c and drivers/char/mem.c. (CVE-2017-7889, Moderate)

  • The inet_csk_clone_lock function in net/ipv4/inet_connection_sock.c in the Linux kernel allows attackers to cause a denial of service (double free) or possibly have unspecified other impact by leveraging use of the accept system call. An unprivileged local user could use this flaw to induce kernel memory corruption on the system, leading to a crash. Due to the nature of the flaw, privilege escalation cannot be fully ruled out, although we believe it is unlikely. (CVE-2017-8890, Moderate)

  • The IPv6 fragmentation implementation in the Linux kernel does not consider that the nexthdr field may be associated with an invalid option, which allows local users to cause a denial of service (out-of-bounds read and BUG) or possibly have unspecified other impact via crafted socket and send system calls. Due to the nature of the flaw, privilege escalation cannot be fully ruled out, although we believe it is unlikely. (CVE-2017-9074, Moderate)

  • The sctp_v6_create_accept_sk function in net/sctp/ipv6.c in the Linux kernel mishandles inheritance, which allows local users to cause a denial of service or possibly have unspecified other impact via crafted system calls, a related issue to CVE-2017-8890. An unprivileged local user could use this flaw to induce kernel memory corruption on the system, leading to a crash. Due to the nature of the flaw, privilege escalation cannot be fully ruled out, although we believe it is unlikely. (CVE-2017-9075, Moderate)

  • The IPv6 DCCP implementation in the Linux kernel mishandles inheritance, which allows local users to cause a denial of service or possibly have unspecified other impact via crafted system calls, a related issue to CVE-2017-8890. An unprivileged local user could use this flaw to induce kernel memory corruption on the system, leading to a crash. Due to the nature of the flaw, privilege escalation cannot be fully ruled out, although we believe it is unlikely. (CVE-2017-9076, Moderate)

  • The tcp_v6_syn_recv_sock function in net/ipv6/tcp_ipv6.c in the Linux kernel mishandles inheritance, which allows local users to cause a denial of service or possibly have unspecified other impact via crafted system calls, a related issue to CVE-2017-8890. An unprivileged local user could use this flaw to induce kernel memory corruption on the system, leading to a crash. Due to the nature of the flaw, privilege escalation cannot be fully ruled out, although we believe it is unlikely. (CVE-2017-9077, Moderate)

  • It was discovered 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. (CVE-2016-9604, Low)

  • A flaw was found in the Linux kernel's implementation of XFS file attributes. Two memory leaks were detected in xfs_attr_shortform_list and xfs_attr3_leaf_list_int when running a docker container backed by xfs/overlay2. A dedicated attacker could possible exhaust all memory and create a denial of service situation. (CVE-2016-9685, Low)