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CVE-2026-97942
x86/alternatives: Exclude text poking against change_page_attr()
Published 2026-09-25 (24 days ago) by the Linux kernel CNA. Subsystem arch/x86. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-97942 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| Debian 14forky | fixed | 7.2.7-1 | Update the kernel and reboot. Fixed in 7.2.7-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.7-1 | Update the kernel and reboot. Fixed in 7.2.7-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
From time to time, the following BUG can be observed in the x86 alternatives patching code [0]: > kernel BUG at arch/x86/kernel/alternative.c:2576! > Oops: invalid opcode: 0000 [#1] SMP NOPTI > CPU: 0 UID: 0 PID: 355 Comm: (udev-worker) Not tainted 7.1.3-1-default #1 PREEMPT(full) openSUSE Tumbleweed 8c1795b03ec64f997e57a8ad38b1161e3b98da64 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS unknown 02/02/2022 > RIP: 0010:__text_poke+0x2aa/0x450 > Call Trace: > <TASK> > smp_text_poke_batch_finish+0x2a7/0x320 > __static_call_transform+0xb7/0x220 > arch_static_call_transform+0x5b/0xb0 > __static_call_init+0xe9/0x270 > static_call_module_notify+0x11f/0x150 > notifier_call_chain+0x61/0xe0 > blocking_notifier_call_chain_robust+0x63/0xc0 > load_module+0x1c92/0x20c0 > init_module_from_file+0xd8/0x140 > idempotent_init_module+0x100/0x2f0 > __x64_sys_finit_module+0x71/0xe0 > do_syscall_64+0xe1/0x610 > entry_SYSCALL_64_after_hwframe+0x76/0x7e which matches the following BUG_ON() in alternative.c: /* * If something went wrong, crash and burn since recovery paths are not * implemented. */ BUG_ON(!pages[0] || (cross_page_boundary && !pages[1])); This can happen if vmalloc_to_page() fails, for any reason. Such can happen if text poking races with CPA, which can possibly result in the collapsing of page tables (or breaking of PMD hugepages). It is not a problem for most users of vmalloc_to_page() (they solely own the vmalloc'd range) but, when CONFIG_ARCH_HAS_EXECMEM_ROX=y, various modules own a single execmem vmalloc range, and can call set_memory_*() in parallel on it. This can happen to race against __text_poke and cause havoc in vmalloc_to_page(). Fix it by excluding against CPA using the init_mm mmap read lock. [ dhansen: Fix up SoB ordering. The actual code flow here was: Pedro=>Lorenzo=>Mike=>Me which is reflected in the SoB chain now. I *believe* Mike simply picked up Lorenzo's update to Pedro's post from the Link ]
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/x86/kernel/alternative.c
- What this is
- X86 ARCHITECTURE (32-BIT AND 64-BIT)MAINTAINERS section matched on arch/x86/ · linux-kernel@vger.kernel.org · Maintained
Show whether Debian builds this, per release
Debian builds this code. Every release below compiles the affected file into the kernels it ships.
- bookworm, trixie, forky, sidy
- y
- built into the kernel image on every flavour - only a patch removes it
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 Debian linux-config packages
Signals
- Published
- 2026-09-25 (24 days ago)source
- CVSS
- no vector published, unrated
- Attack vector
- not published
- EPSS
- 0.20%, higher than 8.9% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- arch/x86
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.15 | 6.18.53 | 281e6f536f2f |
| 6.15 | 7.2.7 | 89c60435b90d |
| 6.15 | 7.3 | 1587d3394e25 |
Why the CNA scored it this way
The kernel CNA published no CVSS vector and no reasoning for CVE-2026-97942, which is why it is shown as unrated rather than given an invented score. 6,405 of the 20,413 CVEs here carry reasoning; this is not one of them.