{"id":"CVE-2025-40009","summary":"fs/proc/task_mmu: check p-\u003evec_buf for NULL","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nfs/proc/task_mmu: check p-\u003evec_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\u003csnip registers, unreliable trace\u003e\n\n[   44.946828] Call Trace:\n[   44.947030]  \u003cTASK\u003e\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-\u003evec_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-\u003evec_buf_index.\n\nFix it by explicitly checking p-\u003evec_buf for NULL before dereferencing.\n\nOther sites that might run into same deref-issue are already (directly or\ntransitively) protected by checking p-\u003evec_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.","modified":"2026-05-18T05:59:31.511883518Z","published":"2025-10-20T15:26:55.208Z","related":["SUSE-SU-2025:21080-1","SUSE-SU-2025:21147-1","SUSE-SU-2025:21180-1","openSUSE-SU-2025:20091-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/40xxx/CVE-2025-40009.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/28aa29986dde79e8466bc87569141291053833f5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a2cb8818a3d915cd33a1e8b2babc1bb0c34862c3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ca988dcdc6683ecd9de5f525ce469588a9141c21"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/40xxx/CVE-2025-40009.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-40009"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"52526ca7fdb905a768a93f8faa418e9b988fc34b"},{"fixed":"ca988dcdc6683ecd9de5f525ce469588a9141c21"},{"fixed":"a2cb8818a3d915cd33a1e8b2babc1bb0c34862c3"},{"fixed":"28aa29986dde79e8466bc87569141291053833f5"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-40009.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.50"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.16.10"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-40009.json"}}],"schema_version":"1.7.5"}