CVE-2024-47707: Vulnerability in Linux Linux

Severity: highType: vulnerabilityCVE-2024-47707

In the Linux kernel, the following vulnerability has been resolved: ipv6: avoid possible NULL deref in rt6_uncached_list_flush_dev() Blamed commit accidentally removed a check for rt->rt6i_idev being NULL, as spotted by syzbot: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 1 UID: 0 PID: 10998 Comm: syz-executor Not tainted 6.11.0-rc6-syzkaller-00208-g625403177711 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024 RIP: 0010:rt6_uncached_list_flush_dev net/ipv6/route.c:177 [inline] RIP: 0010:rt6_disable_ip+0x33e/0x7e0 net/ipv6/route.c:4914 Code: 41 80 3c 04 00 74 0a e8 90 d0 9b f7 48 8b 7c 24 08 48 8b 07 48 89 44 24 10 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 f7 e8 64 d0 9b f7 48 8b 44 24 18 49 39 06 RSP: 0018:ffffc900047374e0 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 1ffff1100fdf8f33 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff88807efc78c0 RBP: ffffc900047375d0 R08: 0000000000000003 R09: fffff520008e6e8c R10: dffffc0000000000 R11: fffff520008e6e8c R12: 1ffff1100fdf8f18 R13: ffff88807efc7998 R14: 0000000000000000 R15: ffff88807efc7930 FS: 0000000000000000(0000) GS:ffff8880b8900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020002a80 CR3: 0000000022f62000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> addrconf_ifdown+0x15d/0x1bd0 net/ipv6/addrconf.c:3856 addrconf_notify+0x3cb/0x1020 notifier_call_chain+0x19f/0x3e0 kernel/notifier.c:93 call_netdevice_notifiers_extack net/core/dev.c:2032 [inline] call_netdevice_notifiers net/core/dev.c:2046 [inline] unregister_netdevice_many_notify+0xd81/0x1c40 net/core/dev.c:11352 unregister_netdevice_many net/core/dev.c:11414 [inline] unregister_netdevice_queue+0x303/0x370 net/core/dev.c:11289 unregister_netdevice include/linux/netdevice.h:3129 [inline] __tun_detach+0x6b9/0x1600 drivers/net/tun.c:685 tun_detach drivers/net/tun.c:701 [inline] tun_chr_close+0x108/0x1b0 drivers/net/tun.c:3510 __fput+0x24a/0x8a0 fs/file_table.c:422 task_work_run+0x24f/0x310 kernel/task_work.c:228 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0xa2f/0x27f0 kernel/exit.c:882 do_group_exit+0x207/0x2c0 kernel/exit.c:1031 __do_sys_exit_group kernel/exit.c:1042 [inline] __se_sys_exit_group kernel/exit.c:1040 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1040 x64_sys_call+0x2634/0x2640 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f1acc77def9 Code: Unable to access opcode bytes at 0x7f1acc77decf. RSP: 002b:00007ffeb26fa738 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f1acc77def9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000043 RBP: 00007f1acc7dd508 R08: 00007ffeb26f84d7 R09: 0000000000000003 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 0000000000000003 R14: 00000000ffffffff R15: 00007ffeb26fa8e0 </TASK> Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:rt6_uncached_list_flush_dev net/ipv6/route.c:177 [inline] RIP: 0010:rt6_disable_ip+0x33e/0x7e0 net/ipv6/route.c:4914 Code: 41 80 3c 04 00 74 0a e8 90 d0 9b f7 48 8b 7c 24 08 48 8b 07 48 89 44 24 10 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 f7 e8 64 d0 9b f7 48 8b 44 24 18 49 39 06 RSP: 0018:ffffc900047374e0 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 1ffff1100fdf8f33 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff88807efc78c0 R ---truncated---

AI Analysis

Technical Summary

CVE-2024-47707 is a vulnerability identified in the Linux kernel's IPv6 networking stack, specifically within the function rt6_uncached_list_flush_dev() in net/ipv6/route.c. The flaw arises from the removal of a critical NULL pointer check for the rt->rt6i_idev pointer, which can lead to a NULL pointer dereference. This vulnerability was detected by syzbot, an automated kernel fuzzer, which triggered a general protection fault due to dereferencing a NULL pointer when handling certain non-canonical IPv6 addresses. The kernel crash occurs during network device teardown or IPv6 address disabling operations, as indicated by the call trace involving functions such as addrconf_ifdown(), unregister_netdevice_many(), and tun_chr_close(). The issue manifests as a kernel oops or panic, causing a denial of service (DoS) by crashing the affected system's kernel. The vulnerability affects multiple versions of the Linux kernel, including recent commits prior to the fix. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The root cause is a missing defensive programming check that should prevent dereferencing a NULL pointer in IPv6 route management code paths. This vulnerability is particularly relevant for systems using IPv6 networking and running Linux kernels with the affected commits.

Potential Impact

For European organizations, the impact of CVE-2024-47707 primarily involves potential denial of service conditions on Linux-based systems that utilize IPv6 networking. This includes servers, network appliances, cloud instances, and embedded devices running vulnerable Linux kernel versions. A successful exploitation leads to kernel crashes, causing service interruptions, potential data loss from abrupt shutdowns, and operational downtime. Critical infrastructure, telecommunications providers, cloud service providers, and enterprises relying on Linux servers for web hosting, virtualization, or container orchestration could face availability disruptions. While this vulnerability does not directly enable privilege escalation or remote code execution, the induced kernel panic can be leveraged in targeted denial of service attacks, especially in environments with high IPv6 traffic or automated network device management. Given the widespread adoption of Linux in European data centers and cloud environments, the vulnerability poses a tangible risk to service continuity and operational resilience.

Mitigation Recommendations

1. Immediate application of the official Linux kernel patch that restores the NULL pointer check in rt6_uncached_list_flush_dev() is critical. Organizations should track kernel updates from trusted sources and apply security patches promptly. 2. For environments where immediate patching is not feasible, consider disabling IPv6 temporarily if it is not essential, to reduce exposure. 3. Implement kernel crash monitoring and automated recovery mechanisms to minimize downtime in case of exploitation. 4. Employ network-level filtering to detect and block malformed or suspicious IPv6 packets that could trigger the vulnerability. 5. Harden system configurations by restricting untrusted users from performing network device teardown or IPv6 address modifications, as these operations are involved in triggering the flaw. 6. Use kernel live patching solutions where available to apply fixes without requiring full system reboots, reducing operational impact. 7. Conduct thorough testing of updated kernels in staging environments before deployment to production to ensure stability and compatibility.