In the Linux kernel, the following vulnerability has been resolved: x86/mm: Disallow vsyscall page read for copy_from_kernel_nofault() When trying to use copy_from_kernel_nofault() to read vsyscall page through a bpf program, the following oops was reported: BUG: unable to handle page fault for address: ffffffffff600000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 3231067 P4D 3231067 PUD 3233067 PMD 3235067 PTE 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 1 PID: 20390 Comm: test_progs ...... 6.7.0+ #58 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) ...... RIP: 0010:copy_from_kernel_nofault+0x6f/0x110 ...... Call Trace: <TASK> ? copy_from_kernel_nofault+0x6f/0x110 bpf_probe_read_kernel+0x1d/0x50 bpf_prog_2061065e56845f08_do_probe_read+0x51/0x8d trace_call_bpf+0xc5/0x1c0 perf_call_bpf_enter.isra.0+0x69/0xb0 perf_syscall_enter+0x13e/0x200 syscall_trace_enter+0x188/0x1c0 do_syscall_64+0xb5/0xe0 entry_SYSCALL_64_after_hwframe+0x6e/0x76 </TASK> ...... ---[ end trace 0000000000000000 ]--- The oops is triggered when: 1) A bpf program uses bpf_probe_read_kernel() to read from the vsyscall page and invokes copy_from_kernel_nofault() which in turn calls __get_user_asm(). 2) Because the vsyscall page address is not readable from kernel space, a page fault exception is triggered accordingly. 3) handle_page_fault() considers the vsyscall page address as a user space address instead of a kernel space address. This results in the fix-up setup by bpf not being applied and a page_fault_oops() is invoked due to SMAP. Considering handle_page_fault() has already considered the vsyscall page address as a userspace address, fix the problem by disallowing vsyscall page read for copy_from_kernel_nofault().
History

Fri, 22 Nov 2024 12:00:00 +0000

Type Values Removed Values Added
References

Sat, 16 Nov 2024 03:00:00 +0000

Type Values Removed Values Added
CPEs cpe:/a:redhat:rhel_eus:9.4

Wed, 13 Nov 2024 15:15:00 +0000

Type Values Removed Values Added
First Time appeared Redhat rhel Eus
CPEs cpe:/a:redhat:rhel_eus:9.2
cpe:/a:redhat:rhel_eus:9.2::nfv
Vendors & Products Redhat rhel Eus

Wed, 13 Nov 2024 02:45:00 +0000

Type Values Removed Values Added
CPEs cpe:/a:redhat:enterprise_linux:9
cpe:/o:redhat:enterprise_linux:9

Tue, 05 Nov 2024 10:45:00 +0000

Type Values Removed Values Added
References

Wed, 11 Sep 2024 13:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2024-04-17T10:27:53.573Z

Updated: 2024-11-05T09:17:57.653Z

Reserved: 2024-02-19T14:20:24.187Z

Link: CVE-2024-26906

cve-icon Vulnrichment

Updated: 2024-08-02T00:21:05.490Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2024-04-17T11:15:11.207

Modified: 2024-11-21T09:03:21.097

Link: CVE-2024-26906

cve-icon Redhat

Severity : Low

Publid Date: 2024-04-17T00:00:00Z

Links: CVE-2024-26906 - Bugzilla