{"id":"CVE-2025-40009","state":"PUBLISHED","title":"fs/proc/task_mmu: check p->vec_buf for NULL","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nfs/proc/task_mmu: check p->vec_buf for NULL\n\nWhen the PAGEMAP_SCAN ioctl is invoked with vec_len = 0 reaches\npagemap_scan_backout_range(), kernel panics with null-ptr-deref:\n\n[   44.936808] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI\n[   44.937797] KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\n[   44.938391] CPU: 1 UID: 0 PID: 2480 Comm: reproducer Not tainted 6.17.0-rc6 #22 PREEMPT(none)\n[   44.939062] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014\n[   44.939935] RIP: 0010:pagemap_scan_thp_entry.isra.0+0x741/0xa80\n\n<snip registers, unreliable trace>\n\n[   44.946828] Call Trace:\n[   44.947030]  <TASK>\n[   44.949219]  pagemap_scan_pmd_entry+0xec/0xfa0\n[   44.952593]  walk_pmd_range.isra.0+0x302/0x910\n[   44.954069]  walk_pud_range.isra.0+0x419/0x790\n[   44.954427]  walk_p4d_range+0x41e/0x620\n[   44.954743]  walk_pgd_range+0x31e/0x630\n[   44.955057]  __walk_page_range+0x160/0x670\n[   44.956883]  walk_page_range_mm+0x408/0x980\n[   44.958677]  walk_page_range+0x66/0x90\n[   44.958984]  do_pagemap_scan+0x28d/0x9c0\n[   44.961833]  do_pagemap_cmd+0x59/0x80\n[   44.962484]  __x64_sys_ioctl+0x18d/0x210\n[   44.962804]  do_syscall_64+0x5b/0x290\n[   44.963111]  entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nvec_len = 0 in pagemap_scan_init_bounce_buffer() means no buffers are\nallocated and p->vec_buf remains set to NULL.\n\nThis breaks an assumption made later in pagemap_scan_backout_range(), that\npage_region is always allocated for p->vec_buf_index.\n\nFix it by explicitly checking p->vec_buf for NULL before dereferencing.\n\nOther sites that might run into same deref-issue are already (directly or\ntransitively) protected by checking p->vec_buf.\n\nNote:\nFrom PAGEMAP_SCAN man page, it seems vec_len = 0 is valid when no output\nis requested and it's only the side effects caller is interested in,\nhence it passes check in pagemap_scan_get_args().\n\nThis issue was found by syzkaller.","publishedAt":"2025-10-20T15:26:55.208Z","updatedAt":"2026-05-11T21:40:42.885Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"52526ca7fdb905a768a93f8faa418e9b988fc34b","status":"affected","lessThan":"ca988dcdc6683ecd9de5f525ce469588a9141c21","versionType":"git"},{"version":"52526ca7fdb905a768a93f8faa418e9b988fc34b","status":"affected","lessThan":"a2cb8818a3d915cd33a1e8b2babc1bb0c34862c3","versionType":"git"},{"version":"52526ca7fdb905a768a93f8faa418e9b988fc34b","status":"affected","lessThan":"28aa29986dde79e8466bc87569141291053833f5","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/proc/task_mmu.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.7","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.7","versionType":"semver"},{"version":"6.12.50","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.16.10","status":"unaffected","lessThanOrEqual":"6.16.*","versionType":"semver"},{"version":"6.17","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/proc/task_mmu.c"]}],"references":["https://git.kernel.org/stable/c/ca988dcdc6683ecd9de5f525ce469588a9141c21","https://git.kernel.org/stable/c/a2cb8818a3d915cd33a1e8b2babc1bb0c34862c3","https://git.kernel.org/stable/c/28aa29986dde79e8466bc87569141291053833f5"],"weaknesses":[],"ingestedAt":"2026-10-29T20:09:09.358Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/40xxx/CVE-2025-40009.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-40009","state":"PUBLISHED","datePublished":"2025-10-20T15:26:55.208Z","dateUpdated":"2026-05-11T21:40:42.885Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T07:20:57.151Z"},"containers":{"cna":{"title":"fs/proc/task_mmu: check p->vec_buf for NULL","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nfs/proc/task_mmu: check p->vec_buf for NULL\n\nWhen the PAGEMAP_SCAN ioctl is invoked with vec_len = 0 reaches\npagemap_scan_backout_range(), kernel panics with null-ptr-deref:\n\n[   44.936808] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI\n[   44.937797] KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\n[   44.938391] CPU: 1 UID: 0 PID: 2480 Comm: reproducer Not tainted 6.17.0-rc6 #22 PREEMPT(none)\n[   44.939062] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014\n[   44.939935] RIP: 0010:pagemap_scan_thp_entry.isra.0+0x741/0xa80\n\n<snip registers, unreliable trace>\n\n[   44.946828] Call Trace:\n[   44.947030]  <TASK>\n[   44.949219]  pagemap_scan_pmd_entry+0xec/0xfa0\n[   44.952593]  walk_pmd_range.isra.0+0x302/0x910\n[   44.954069]  walk_pud_range.isra.0+0x419/0x790\n[   44.954427]  walk_p4d_range+0x41e/0x620\n[   44.954743]  walk_pgd_range+0x31e/0x630\n[   44.955057]  __walk_page_range+0x160/0x670\n[   44.956883]  walk_page_range_mm+0x408/0x980\n[   44.958677]  walk_page_range+0x66/0x90\n[   44.958984]  do_pagemap_scan+0x28d/0x9c0\n[   44.961833]  do_pagemap_cmd+0x59/0x80\n[   44.962484]  __x64_sys_ioctl+0x18d/0x210\n[   44.962804]  do_syscall_64+0x5b/0x290\n[   44.963111]  entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nvec_len = 0 in pagemap_scan_init_bounce_buffer() means no buffers are\nallocated and p->vec_buf remains set to NULL.\n\nThis breaks an assumption made later in pagemap_scan_backout_range(), that\npage_region is always allocated for p->vec_buf_index.\n\nFix it by explicitly checking p->vec_buf for NULL before dereferencing.\n\nOther sites that might run into same deref-issue are already (directly or\ntransitively) protected by checking p->vec_buf.\n\nNote:\nFrom PAGEMAP_SCAN man page, it seems vec_len = 0 is valid when no output\nis requested and it's only the side effects caller is interested in,\nhence it passes check in pagemap_scan_get_args().\n\nThis issue was found by syzkaller."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"52526ca7fdb905a768a93f8faa418e9b988fc34b","status":"affected","lessThan":"ca988dcdc6683ecd9de5f525ce469588a9141c21","versionType":"git"},{"version":"52526ca7fdb905a768a93f8faa418e9b988fc34b","status":"affected","lessThan":"a2cb8818a3d915cd33a1e8b2babc1bb0c34862c3","versionType":"git"},{"version":"52526ca7fdb905a768a93f8faa418e9b988fc34b","status":"affected","lessThan":"28aa29986dde79e8466bc87569141291053833f5","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/proc/task_mmu.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.7","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.7","versionType":"semver"},{"version":"6.12.50","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.16.10","status":"unaffected","lessThanOrEqual":"6.16.*","versionType":"semver"},{"version":"6.17","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/proc/task_mmu.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/ca988dcdc6683ecd9de5f525ce469588a9141c21"},{"url":"https://git.kernel.org/stable/c/a2cb8818a3d915cd33a1e8b2babc1bb0c34862c3"},{"url":"https://git.kernel.org/stable/c/28aa29986dde79e8466bc87569141291053833f5"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T21:40:42.885Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"6.12.50"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"6.16.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"6.17"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}