CVE-2024-26906 Affecting dlm-kmp-default package, versions <6.4.0-150600.23.7.3
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-SLES156-DLMKMPDEFAULT-7713968
- published20 Aug 2024
- disclosed25 Jun 2024
Introduced: 25 Jun 2024
CVE-2024-26906 (opens in a new tab)How to fix?
Upgrade SLES:15.6 dlm-kmp-default to version 6.4.0-150600.23.7.3 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream dlm-kmp-default package and not the dlm-kmp-default package as distributed by SLES.
See How to fix? for SLES:15.6 relevant fixed versions and status.
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:
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().
Because the vsyscall page address is not readable from kernel space, a page fault exception is triggered accordingly.
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().
References
- https://www.suse.com/security/cve/CVE-2024-26906.html
- https://bugzilla.suse.com/1223202
- 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://lists.debian.org/debian-lts-announce/2024/06/msg00017.html