CVE-2026-80688

What the bug is

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.

Where it lives

The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.

arch/riscv/kernel/unaligned_access_speed.c

What this is

RISC-V ARCHITECTUREMAINTAINERS section matched on arch/riscv/ · linux-riscv@lists.infradead.org · Supported

Check it on the machine

grep -w CONFIG_RISCV_MISALIGNED /boot/config-$(uname -r)

Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.

Show whether Debian builds this, per release

Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed. The build rule could not be established for 1 release, so nothing is claimed about those.

• bookworm?
• trixieYnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt/arm64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, s390x/s390x
• forky, sidYnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt-amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt-arm64, armhf/armmp, armhf/armmp-lpae, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, s390x/s390x

?

not established - no Makefile entry for the affected file

Y

built in where it is built at all; some flavours do not build it

Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.

Build switch

CONFIG_RISCV_MISALIGNED

From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages

Signals

Published

2026-08-28 (2 months ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.21%, higher than 10.0% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

unimportantsource

Subsystem

arch/riscv

Upstream fixes

The versions the CNA records as introducing and fixing this, and the commit for each. source

Introduced	Fixed in	Commit
6.15	6.18.44	01bd01b61ad9
6.15	7.1.8	25f228e6ac57
6.15	7.2	f51fed61eea0
6.13.11	0	0
6.14.2	0	0