Red Hat Security Advisory: kernel security, bug fix, and enhancement update

Important

A flaw was found in the Linux kernel. A use-after-free vulnerability exists in the traffic control `act_ct` path when it is incorrectly configured with non-ingress egress qdiscs (queueing disciplines). This can allow a local user with specific privileges to trigger a kernel crash, leading to a denial of service. In some cases, this vulnerability may also be exploited for privilege escalation.

CWE-416 - Use After Free

A flaw was found in the Linux kernel's netfilter subsystem, specifically within the `nf_conntrack_h323` module. This vulnerability occurs in the `DecodeQ931()` function when processing a zero-length value from a packet. An integer underflow during a length calculation results in a large, incorrect value being passed to a subsequent function, leading to an out-of-bounds read. This could allow an attacker to cause a denial of service or potentially disclose sensitive information.

CWE-125 - Out-of-bounds Read

A flaw was found in the Linux kernel's Multipath TCP (MPTCP) implementation. Due to incorrect memory allocation for IPv6 subflow child sockets, a use-after-free vulnerability exists. A remote attacker could exploit this by triggering concurrent lookups in the kernel's hash table, potentially leading to a denial of service or arbitrary code execution.

CWE-763 - Release of Invalid Pointer or Reference

A flaw was found in the Linux kernel's Distributed Lock Manager (dlm) module. An attacker could send specially crafted network messages with an oversized length parameter to the dlm_dump_rsb_name() function. This lack of validation can lead to an out-of-bounds write in the dlm_search_rsb_tree() function, potentially causing a buffer overflow. This vulnerability could allow for denial of service or, in some cases, arbitrary code execution.

CWE-130 - Improper Handling of Length Parameter Inconsistency

A flaw was found in the Linux kernel. A race condition exists in the TCP (Transmission Control Protocol) IPv6 (Internet Protocol version 6) socket handling, specifically within the tcp_v6_syn_recv_sock() function. This occurs because a child socket becomes visible in the TCP hash table before its IPv6-specific information is fully initialized. A remote attacker could potentially exploit this timing window, leading to an unstable system state or unexpected behavior, which may result in a denial of service (DoS).

CWE-821 - Incorrect Synchronization

A flaw was found in the Linux kernel's ALSA (Advanced Linux Sound Architecture) USB audio subsystem. An inconsistency in how USB audio playback and capture streams are handled can lead to an out-of-bounds write to a memory buffer. This can result in a system crash, causing a denial of service for a local user.

CWE-787 - Out-of-bounds Write

A flaw was found in the Netfilter flowtable component of the Linux kernel. This vulnerability occurs because the system does not strictly check the maximum number of hardware offload actions for IPv6, allowing it to process more actions than supported. This could potentially lead to system instability or a denial of service (DoS) condition, where the affected system becomes unresponsive.

CWE-770 - Allocation of Resources Without Limits or Throttling

A flaw was found in the Linux kernel's Remote Direct Memory Access (RDMA) subsystem, specifically within the `rxe` driver. An error in the `rxe_srq_from_init` function's memory management can lead to a double free vulnerability. This occurs when an attempt to copy data to user space fails, causing the same memory region to be freed twice. A local attacker could potentially exploit this flaw to cause a denial of service (DoS) by crashing the system.

A flaw was found in the Linux kernel's ALSA (Advanced Linux Sound Architecture) aloop driver. This Use-After-Free (UAF) vulnerability occurs when loopback_check_format() stops the capture side during a format change, while a concurrent close operation detaches or frees the runtime. An attacker could potentially exploit this to cause a system crash or achieve arbitrary code execution.

CWE-364 - Signal Handler Race Condition

A flaw was found in the Linux kernel's RDMA/mlx4 component. This vulnerability arises from the incorrect use of Read-Copy Update (RCU) in the `mlx4_srq_event()` function. An attacker could potentially trigger an event before the `srq` object is fully initialized, leading to a system crash. This could result in a Denial of Service (DoS) for the affected system.

CWE-366 - Race Condition within a Thread