{"id":"CVE-2026-97942","state":"PUBLISHED","title":"x86/alternatives: Exclude text poking against change_page_attr()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nx86/alternatives: Exclude text poking against change_page_attr()\n\nFrom time to time, the following BUG can be observed\nin the x86 alternatives patching code [0]:\n\n  > kernel BUG at arch/x86/kernel/alternative.c:2576!\n  > Oops: invalid opcode: 0000 [#1] SMP NOPTI\n  > CPU: 0 UID: 0 PID: 355 Comm: (udev-worker) Not tainted 7.1.3-1-default #1 PREEMPT(full) openSUSE Tumbleweed  8c1795b03ec64f997e57a8ad38b1161e3b98da64\n  > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS unknown 02/02/2022\n  > RIP: 0010:__text_poke+0x2aa/0x450\n  > Call Trace:\n  >  <TASK>\n  >  smp_text_poke_batch_finish+0x2a7/0x320\n  >  __static_call_transform+0xb7/0x220\n  >  arch_static_call_transform+0x5b/0xb0\n  >  __static_call_init+0xe9/0x270\n  >  static_call_module_notify+0x11f/0x150\n  >  notifier_call_chain+0x61/0xe0\n  >  blocking_notifier_call_chain_robust+0x63/0xc0\n  >  load_module+0x1c92/0x20c0\n  >  init_module_from_file+0xd8/0x140\n  >  idempotent_init_module+0x100/0x2f0\n  >  __x64_sys_finit_module+0x71/0xe0\n  >  do_syscall_64+0xe1/0x610\n  >  entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nwhich matches the following BUG_ON() in alternative.c:\n\n\t/*\n\t * If something went wrong, crash and burn since recovery paths are not\n\t * implemented.\n\t */\n\tBUG_ON(!pages[0] || (cross_page_boundary && !pages[1]));\n\nThis can happen if vmalloc_to_page() fails, for any reason. Such can happen\nif text poking races with CPA, which can possibly result in the collapsing\nof page tables (or breaking of PMD hugepages). It is not a problem for most\nusers of vmalloc_to_page() (they solely own the vmalloc'd range) but, when\nCONFIG_ARCH_HAS_EXECMEM_ROX=y, various modules own a single execmem vmalloc\nrange, and can call set_memory_*() in parallel on it. This can happen to\nrace against __text_poke and cause havoc in vmalloc_to_page().\n\nFix it by excluding against CPA using the init_mm mmap read lock.\n\n[ dhansen: Fix up SoB ordering. The actual code flow here was:\n\t   Pedro=>Lorenzo=>Mike=>Me which is reflected in the SoB chain\n\t   now. I *believe* Mike simply picked up Lorenzo's update to\n\t   Pedro's post from the Link ]","publishedAt":"2026-09-25T10:22:54.188Z","updatedAt":"2026-10-19T09:11:08.757Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"64f6a4e10c05ed527f0f24b7954964255e0d3535","status":"affected","lessThan":"281e6f536f2f3f95d91938c5bd7ba9bcb4c1049d","versionType":"git"},{"version":"64f6a4e10c05ed527f0f24b7954964255e0d3535","status":"affected","lessThan":"89c60435b90d32ab5e3a39da3ae73d463d07debe","versionType":"git"},{"version":"64f6a4e10c05ed527f0f24b7954964255e0d3535","status":"affected","lessThan":"1587d3394e254639cc36516256031334095e6ef3","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/kernel/alternative.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.15","versionType":"semver"},{"version":"6.18.53","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.7","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/kernel/alternative.c"]}],"references":["https://git.kernel.org/stable/c/281e6f536f2f3f95d91938c5bd7ba9bcb4c1049d","https://git.kernel.org/stable/c/89c60435b90d32ab5e3a39da3ae73d463d07debe","https://git.kernel.org/stable/c/1587d3394e254639cc36516256031334095e6ef3"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/97xxx/CVE-2026-97942.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-97942","state":"PUBLISHED","datePublished":"2026-09-25T10:22:54.188Z","dateUpdated":"2026-10-19T09:11:08.757Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:18:58.204Z"},"containers":{"cna":{"title":"x86/alternatives: Exclude text poking against change_page_attr()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nx86/alternatives: Exclude text poking against change_page_attr()\n\nFrom time to time, the following BUG can be observed\nin the x86 alternatives patching code [0]:\n\n  > kernel BUG at arch/x86/kernel/alternative.c:2576!\n  > Oops: invalid opcode: 0000 [#1] SMP NOPTI\n  > CPU: 0 UID: 0 PID: 355 Comm: (udev-worker) Not tainted 7.1.3-1-default #1 PREEMPT(full) openSUSE Tumbleweed  8c1795b03ec64f997e57a8ad38b1161e3b98da64\n  > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS unknown 02/02/2022\n  > RIP: 0010:__text_poke+0x2aa/0x450\n  > Call Trace:\n  >  <TASK>\n  >  smp_text_poke_batch_finish+0x2a7/0x320\n  >  __static_call_transform+0xb7/0x220\n  >  arch_static_call_transform+0x5b/0xb0\n  >  __static_call_init+0xe9/0x270\n  >  static_call_module_notify+0x11f/0x150\n  >  notifier_call_chain+0x61/0xe0\n  >  blocking_notifier_call_chain_robust+0x63/0xc0\n  >  load_module+0x1c92/0x20c0\n  >  init_module_from_file+0xd8/0x140\n  >  idempotent_init_module+0x100/0x2f0\n  >  __x64_sys_finit_module+0x71/0xe0\n  >  do_syscall_64+0xe1/0x610\n  >  entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nwhich matches the following BUG_ON() in alternative.c:\n\n\t/*\n\t * If something went wrong, crash and burn since recovery paths are not\n\t * implemented.\n\t */\n\tBUG_ON(!pages[0] || (cross_page_boundary && !pages[1]));\n\nThis can happen if vmalloc_to_page() fails, for any reason. Such can happen\nif text poking races with CPA, which can possibly result in the collapsing\nof page tables (or breaking of PMD hugepages). It is not a problem for most\nusers of vmalloc_to_page() (they solely own the vmalloc'd range) but, when\nCONFIG_ARCH_HAS_EXECMEM_ROX=y, various modules own a single execmem vmalloc\nrange, and can call set_memory_*() in parallel on it. This can happen to\nrace against __text_poke and cause havoc in vmalloc_to_page().\n\nFix it by excluding against CPA using the init_mm mmap read lock.\n\n[ dhansen: Fix up SoB ordering. The actual code flow here was:\n\t   Pedro=>Lorenzo=>Mike=>Me which is reflected in the SoB chain\n\t   now. I *believe* Mike simply picked up Lorenzo's update to\n\t   Pedro's post from the Link ]"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"64f6a4e10c05ed527f0f24b7954964255e0d3535","status":"affected","lessThan":"281e6f536f2f3f95d91938c5bd7ba9bcb4c1049d","versionType":"git"},{"version":"64f6a4e10c05ed527f0f24b7954964255e0d3535","status":"affected","lessThan":"89c60435b90d32ab5e3a39da3ae73d463d07debe","versionType":"git"},{"version":"64f6a4e10c05ed527f0f24b7954964255e0d3535","status":"affected","lessThan":"1587d3394e254639cc36516256031334095e6ef3","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/kernel/alternative.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.15","versionType":"semver"},{"version":"6.18.53","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.7","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/kernel/alternative.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/281e6f536f2f3f95d91938c5bd7ba9bcb4c1049d"},{"url":"https://git.kernel.org/stable/c/89c60435b90d32ab5e3a39da3ae73d463d07debe"},{"url":"https://git.kernel.org/stable/c/1587d3394e254639cc36516256031334095e6ef3"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T09:11:08.757Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.15","versionEndExcluding":"6.18.53"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.15","versionEndExcluding":"7.2.7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.15","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}