UBUNTU-CVE-2024-26906
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().
02 / AFFECTED SOFTWARE
Affected packages
29 explicit affected versions
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35 explicit affected versions
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37 explicit affected versions
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29 explicit affected versions
13 explicit affected versions
49 explicit affected versions
47 explicit affected versions
9 explicit affected versions
33 explicit affected versions
23 explicit affected versions
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37 explicit affected versions
30 explicit affected versions
46 explicit affected versions
10 explicit affected versions
26 explicit affected versions
1 explicit affected versions
13 explicit affected versions
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49 explicit affected versions
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51 explicit affected versions
2 explicit affected versions
12 explicit affected versions
35 explicit affected versions
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10 explicit affected versions
12 explicit affected versions
12 explicit affected versions
44 explicit affected versions
16 explicit affected versions
3 explicit affected versions
13 explicit affected versions
26 explicit affected versions
35 explicit affected versions
37 explicit affected versions
14 explicit affected versions
38 explicit affected versions
39 explicit affected versions
9 explicit affected versions
38 explicit affected versions
11 explicit affected versions
46 explicit affected versions
8 explicit affected versions
7 explicit affected versions
20 explicit affected versions
4 explicit affected versions
1 explicit affected versions
1 explicit affected versions
44 explicit affected versions
13 explicit affected versions
43 explicit affected versions
10 explicit affected versions
8 explicit affected versions
14 explicit affected versions
4 explicit affected versions
11 explicit affected versions
1 explicit affected versions
11 explicit affected versions
116 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
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().
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/32019c659ecfe1d92e3bf9fcdfbb11a7c70acd58
- https://git.kernel.org/stable/c/29bd6f86904682adafe9affbc7f79b14defcaff8
- https://git.kernel.org/stable/c/32019c659ecfe1d92e3bf9fcdfbb11a7c70acd58
- https://git.kernel.org/stable/c/57f78c46f08198e1be08ffe99c4c1ccc12855bf5
- https://git.kernel.org/stable/c/6e4694e65b6db4c3de125115dd4f55848cc48381
- https://git.kernel.org/stable/c/e8a67fe34b76a49320b33032228a794f40b0316b
- https://git.kernel.org/stable/c/f175de546a3eb77614d94d4c02550181c0a8493e
- https://ubuntu.com/security/CVE-2024-26906
- https://ubuntu.com/security/notices/USN-6820-1
- https://ubuntu.com/security/notices/USN-6820-2
- https://ubuntu.com/security/notices/USN-6821-1
- https://ubuntu.com/security/notices/USN-6821-2
- https://ubuntu.com/security/notices/USN-6821-3
- https://ubuntu.com/security/notices/USN-6821-4
- https://ubuntu.com/security/notices/USN-6828-1
- https://ubuntu.com/security/notices/USN-6871-1
- https://ubuntu.com/security/notices/USN-6892-1
- https://ubuntu.com/security/notices/USN-6919-1
- https://www.cve.org/CVERecord?id=CVE-2024-26906