CVE-2024-42106 in Linux
Summary
by MITRE • 07/30/2024
In the Linux kernel, the following vulnerability has been resolved:
inet_diag: Initialize pad field in struct inet_diag_req_v2
KMSAN reported uninit-value access in raw_lookup() [1]. Diag for raw
sockets uses the pad field in struct inet_diag_req_v2 for the underlying protocol. This field corresponds to the sdiag_raw_protocol field in struct inet_diag_req_raw.
inet_diag_get_exact_compat() converts inet_diag_req to inet_diag_req_v2, but leaves the pad field uninitialized. So the issue occurs when raw_lookup() accesses the sdiag_raw_protocol field.
Fix this by initializing the pad field in inet_diag_get_exact_compat(). Also, do the same fix in inet_diag_dump_compat() to avoid the similar issue in the future.
[1]
BUG: KMSAN: uninit-value in raw_lookup net/ipv4/raw_diag.c:49 [inline]
BUG: KMSAN: uninit-value in raw_sock_get+0x657/0x800 net/ipv4/raw_diag.c:71 raw_lookup net/ipv4/raw_diag.c:49 [inline]
raw_sock_get+0x657/0x800 net/ipv4/raw_diag.c:71 raw_diag_dump_one+0xa1/0x660 net/ipv4/raw_diag.c:99 inet_diag_cmd_exact+0x7d9/0x980 inet_diag_get_exact_compat net/ipv4/inet_diag.c:1404 [inline]
inet_diag_rcv_msg_compat+0x469/0x530 net/ipv4/inet_diag.c:1426 sock_diag_rcv_msg+0x23d/0x740 net/core/sock_diag.c:282 netlink_rcv_skb+0x537/0x670 net/netlink/af_netlink.c:2564 sock_diag_rcv+0x35/0x40 net/core/sock_diag.c:297 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline]
netlink_unicast+0xe74/0x1240 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x10c6/0x1260 net/netlink/af_netlink.c:1905 sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg+0x332/0x3d0 net/socket.c:745 ____sys_sendmsg+0x7f0/0xb70 net/socket.c:2585 ___sys_sendmsg+0x271/0x3b0 net/socket.c:2639 __sys_sendmsg net/socket.c:2668 [inline]
__do_sys_sendmsg net/socket.c:2677 [inline]
__se_sys_sendmsg net/socket.c:2675 [inline]
__x64_sys_sendmsg+0x27e/0x4a0 net/socket.c:2675 x64_sys_call+0x135e/0x3ce0 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xd9/0x1e0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f
Uninit was stored to memory at: raw_sock_get+0x650/0x800 net/ipv4/raw_diag.c:71 raw_diag_dump_one+0xa1/0x660 net/ipv4/raw_diag.c:99 inet_diag_cmd_exact+0x7d9/0x980 inet_diag_get_exact_compat net/ipv4/inet_diag.c:1404 [inline]
inet_diag_rcv_msg_compat+0x469/0x530 net/ipv4/inet_diag.c:1426 sock_diag_rcv_msg+0x23d/0x740 net/core/sock_diag.c:282 netlink_rcv_skb+0x537/0x670 net/netlink/af_netlink.c:2564 sock_diag_rcv+0x35/0x40 net/core/sock_diag.c:297 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline]
netlink_unicast+0xe74/0x1240 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x10c6/0x1260 net/netlink/af_netlink.c:1905 sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg+0x332/0x3d0 net/socket.c:745 ____sys_sendmsg+0x7f0/0xb70 net/socket.c:2585 ___sys_sendmsg+0x271/0x3b0 net/socket.c:2639 __sys_sendmsg net/socket.c:2668 [inline]
__do_sys_sendmsg net/socket.c:2677 [inline]
__se_sys_sendmsg net/socket.c:2675 [inline]
__x64_sys_sendmsg+0x27e/0x4a0 net/socket.c:2675 x64_sys_call+0x135e/0x3ce0 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xd9/0x1e0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f
Local variable req.i created at: inet_diag_get_exact_compat net/ipv4/inet_diag.c:1396 [inline]
inet_diag_rcv_msg_compat+0x2a6/0x530 net/ipv4/inet_diag.c:1426 sock_diag_rcv_msg+0x23d/0x740 net/core/sock_diag.c:282
CPU: 1 PID: 8888 Comm: syz-executor.6 Not tainted 6.10.0-rc4-00217-g35bb670d65fc #32 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 04/01/2014
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Analysis
by VulDB Data Team • 07/19/2025
The vulnerability described in CVE-2024-42106 resides within the Linux kernel's networking subsystem, specifically in the inet_diag component responsible for diagnostic operations on network sockets. This issue manifests as an uninitialized memory access that can potentially lead to unpredictable behavior or exploitation. The flaw occurs when handling raw socket diagnostics, where the pad field in the struct inet_diag_req_v2 structure is not properly initialized during conversion from the older inet_diag_req structure. This uninitialized field subsequently gets accessed by the raw_lookup function, which interprets it as the sdiag_raw_protocol field, leading to a potential security risk. The vulnerability was detected by KMSAN (Kernel Memory Sanitizer), which flagged an uninitialized value access in the raw_diag.c file during diagnostic operations.
The technical root cause involves a conversion function inet_diag_get_exact_compat that transforms data structures for compatibility purposes but fails to initialize the pad field in struct inet_diag_req_v2. This field serves a specific purpose in raw socket diagnostics by mapping to the sdiag_raw_protocol field within the underlying socket structure. When raw_lookup attempts to access this uninitialized value, it may read garbage data from memory, which could be exploited by an attacker to infer system state or potentially manipulate the diagnostic process. The issue is particularly concerning because it occurs during normal network diagnostic operations, making it accessible through standard kernel interfaces. The vulnerability demonstrates a classic case of uninitialized memory access, which is categorized under CWE-457: Use of Uninitialized Variable, and represents a potential information disclosure or privilege escalation vector depending on the execution context and attack surface.
The operational impact of this vulnerability extends beyond simple memory corruption, as it could enable an attacker to perform reconnaissance or manipulate diagnostic responses in ways that might not be immediately obvious. When network diagnostic tools interact with raw sockets, the uninitialized memory could contain sensitive information or create predictable patterns that could be exploited. The vulnerability affects systems running Linux kernels where inet_diag functionality is active, particularly those using raw socket diagnostics through netlink communication. Attackers could potentially leverage this issue to gain insights into kernel memory layout or to craft more sophisticated attacks against network services. The attack surface is broad given that raw socket diagnostics are used for network monitoring and debugging purposes across various network applications and system management tools.
Mitigation strategies for CVE-2024-42106 focus on ensuring proper initialization of memory fields during data structure conversions within the kernel. The fix implemented addresses the root cause by initializing the pad field in both inet_diag_get_exact_compat and inet_diag_dump_compat functions, thereby preventing the uninitialized memory access. This approach aligns with the principle of least privilege and secure coding practices recommended in the ATT&CK framework for kernel-level vulnerabilities. System administrators should apply the relevant kernel patches as soon as they become available, as the vulnerability affects core networking functionality. Additionally, monitoring for unusual diagnostic activity or unexpected memory access patterns could help detect exploitation attempts. The fix also includes proactive measures to prevent similar issues in future development, emphasizing the importance of thorough memory initialization in kernel code. Organizations should ensure their systems are updated to kernel versions that include this patch, particularly those running network monitoring or diagnostic tools that interact with raw sockets through the inet_diag interface.