CVE-2026-80688
Received Received - Intake

Kernel Page Fault in Linux RISC-V Due to Uninitialized Memory Access

Publication date: 2026-08-28

Last updated on: 2026-08-28

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: riscv: drop __init from vec_check_unaligned_access_speed_all_cpus This function runs within a kthread and need not necessarily finish before system finishes boot and free_initmem() unmaps the .init.text section. This function makes calls to SBI for probing unaligned access speed, and if this is slow for some reason (say some debug prints were added to SBI), the kthread can still be running at this point and result in an instruction page fault when trying to fetch from the freed region. [ 25.642087] Unable to handle kernel paging request at virtual address ffffffff80a04ef8 [ 25.646694] Current vec_check_unali pgtable: 4K pagesize, 48-bit VAs, pgdp=0x00004000316e9000 [ 25.653170] [ffffffff80a04ef8] pgd=000010004be7e401, p4d=000010004be7e401, pud=000010004be7e001, pmd=000010000c3000e3 [ 25.661244] Oops [#1] [ 25.662997] Modules linked in: [ 25.665357] CPU: 3 UID: 0 PID: 42 Comm: vec_check_unali Not tainted 7.0.0-tt-blackhole-asrinivasan-00007-g30ff73f18211 #570 PREEMPTLAZY [ 25.674669] Hardware name: Tenstorrent Blackhole (DT) [ 25.678545] epc : vec_check_unaligned_access_speed_all_cpus+0x18/0x2c [ 25.683458] ra : vec_check_unaligned_access_speed_all_cpus+0x18/0x2c [ 25.688372] epc : ffffffff80a04ef8 ra : ffffffff80a04ef8 sp : ffff8f8000203e20 [ 25.693874] gp : ffffffff814dc168 tp : ffffaf8001ad9900 t0 : 0000000000000000 [ 25.699401] t1 : fffffffffffffff0 t2 : ffffaf8001ad9a10 s0 : ffff8f8000203e30 [ 25.704912] s1 : ffffaf80018dc780 a0 : 0000000000000000 a1 : 0000000000000002 [ 25.710407] a2 : 00000000000001f0 a3 : 0000000000000018 a4 : 0000000000000000 [ 25.715917] a5 : 0000000000000000 a6 : ffffaf8001c03d98 a7 : ffffaf8001c03e30 [ 25.721419] s2 : ffff8f8000023c98 s3 : ffffaf8001aa1240 s4 : ffffffff80a04ee0 [ 25.726937] s5 : 0000000000000000 s6 : 0000000000000000 s7 : 0000000000000000 [ 25.732450] s8 : 0000000000000000 s9 : 0000000000000000 s10: 0000000000000000 [ 25.737944] s11: 0000000000000000 t3 : 0000000000000002 t4 : 0000000000000402 [ 25.743481] t5 : 0000000000000040 t6 : 0000000000000004 ssp : 0000000000000000 [ 25.749024] status: 0000000200000120 badaddr: ffffffff80a04ef8 cause: 000000000000000c [ 25.755060] [<ffffffff80a04ef8>] vec_check_unaligned_access_speed_all_cpus+0x18/0x2c [ 25.760964] [<ffffffff80047a10>] kthread+0xd8/0xfc [ 25.764660] [<ffffffff80010c48>] ret_from_fork_kernel+0x18/0x1c4 [ 25.769220] [<ffffffff80895fe6>] ret_from_fork_kernel_asm+0x16/0x18 [ 25.774018] Code: cccc cccc cccc cccc cccc cccc cccc cccc cccc cccc (cccc) cccc Drop __init from its signature so that this doesn't happen.

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Meta Information

Published
2026-08-28
Last Modified
2026-08-28
Generated
2026-08-28
AI Q&A
2026-08-28
EPSS Evaluated
N/A
NVD
CVE-2026-80688
EUVD
EUVD-2026-67423

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux_kernel linux_kernel 7.0.0

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a Linux kernel vulnerability where a function vec_check_unaligned_access_speed_all_cpus runs in a kernel thread after system boot. The function is marked with __init which causes its memory to be freed once boot completes. If the function is still running when memory is freed, it can trigger a page fault when accessing freed memory, leading to a kernel crash.

Detection Guidance

This vulnerability is specific to the Linux kernel and may cause kernel oops or crashes during boot or early system initialization. Check kernel logs for errors related to vec_check_unaligned_access_speed_all_cpus or page faults in .init.text sections.

Impact Analysis

This vulnerability can cause system instability or crashes. If the affected function is still running during boot cleanup, it may access freed memory, resulting in a kernel panic or system failure. This could lead to unexpected reboots or service disruptions.

Mitigation Strategies

Update the Linux kernel to a patched version where this issue is resolved. The fix involves removing the __init annotation from vec_check_unaligned_access_speed_all_cpus to prevent page faults during boot.

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