CVE-2024-26906

CVE Details

Release Date:

2024-04-17

Description

In the Linux kernel, the following vulnerability has been resolved:\nx86/mm: Disallow vsyscall page read for copy_from_kernel_nofault()\nWhen trying to use copy_from_kernel_nofault() to read vsyscall page\nthrough a bpf program, the following oops was reported:\nBUG: unable to handle page fault for address: ffffffffff600000\n#PF: supervisor read access in kernel mode\n#PF: error_code(0x0000) - not-present page\nPGD 3231067 P4D 3231067 PUD 3233067 PMD 3235067 PTE 0\nOops: 0000 [#1] PREEMPT SMP PTI\nCPU: 1 PID: 20390 Comm: test_progs ...... 6.7.0+ #58\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996) ......\nRIP: 0010:copy_from_kernel_nofault+0x6f/0x110\n......\nCall Trace:\n\n? copy_from_kernel_nofault+0x6f/0x110\nbpf_probe_read_kernel+0x1d/0x50\nbpf_prog_2061065e56845f08_do_probe_read+0x51/0x8d\ntrace_call_bpf+0xc5/0x1c0\nperf_call_bpf_enter.isra.0+0x69/0xb0\nperf_syscall_enter+0x13e/0x200\nsyscall_trace_enter+0x188/0x1c0\ndo_syscall_64+0xb5/0xe0\nentry_SYSCALL_64_after_hwframe+0x6e/0x76\n\n......\n---[ end trace 0000000000000000 ]---\nThe oops is triggered when:\n1) A bpf program uses bpf_probe_read_kernel() to read from the vsyscall\npage and invokes copy_from_kernel_nofault() which in turn calls\n__get_user_asm().\n2) Because the vsyscall page address is not readable from kernel space,\na page fault exception is triggered accordingly.\n3) handle_page_fault() considers the vsyscall page address as a user\nspace address instead of a kernel space address. This results in the\nfix-up setup by bpf not being applied and a page_fault_oops() is invoked\ndue to SMAP.\nConsidering handle_page_fault() has already considered the vsyscall page\naddress as a userspace address, fix the problem by disallowing vsyscall\npage read for copy_from_kernel_nofault().

See more information about CVE-2024-26906 from MITRE CVE dictionary and NIST NVD

CVSS Scoring

NOTE: The following CVSS v3.1 metrics and score provided are preliminary and subject to review.

Base Score:	5.5	CVSS Vector:	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector:	Local network	Attack Complexity:	Low
Privileges Required:	Low	User Interaction:	None
Scope:	Unchanged	Confidentiality Impact:	None
Integrity Impact:	None	Availability Impact:	High

Errata information

Platform	Errata	Release Date
Oracle Linux version 8 (kernel)	ELSA-2024-4211	2024-07-02
Oracle Linux version 9 (kernel)	ELSA-2024-9315	2024-11-14