{"id":"CVE-2026-31592","summary":"KVM: SEV: Protect *all* of sev_mem_enc_register_region() with kvm-\u003elock","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SEV: Protect *all* of sev_mem_enc_register_region() with kvm-\u003elock\n\nTake and hold kvm-\u003elock for before checking sev_guest() in\nsev_mem_enc_register_region(), as sev_guest() isn't stable unless kvm-\u003elock\nis held (or KVM can guarantee KVM_SEV_INIT{2} has completed and can't\nrollack state).  If KVM_SEV_INIT{2} fails, KVM can end up trying to add to\na not-yet-initialized sev-\u003eregions_list, e.g. triggering a #GP\n\n  Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI\n  KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\n  CPU: 110 UID: 0 PID: 72717 Comm: syz.15.11462 Tainted: G     U  W  O        6.16.0-smp-DEV #1 NONE\n  Tainted: [U]=USER, [W]=WARN, [O]=OOT_MODULE\n  Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 12.52.0-0 10/28/2024\n  RIP: 0010:sev_mem_enc_register_region+0x3f0/0x4f0 ../include/linux/list.h:83\n  Code: \u003c41\u003e 80 3c 04 00 74 08 4c 89 ff e8 f1 c7 a2 00 49 39 ed 0f 84 c6 00\n  RSP: 0018:ffff88838647fbb8 EFLAGS: 00010256\n  RAX: dffffc0000000000 RBX: 1ffff92015cf1e0b RCX: dffffc0000000000\n  RDX: 0000000000000000 RSI: 0000000000001000 RDI: ffff888367870000\n  RBP: ffffc900ae78f050 R08: ffffea000d9e0007 R09: 1ffffd4001b3c000\n  R10: dffffc0000000000 R11: fffff94001b3c001 R12: 0000000000000000\n  R13: ffff8982ab0bde00 R14: ffffc900ae78f058 R15: 0000000000000000\n  FS:  00007f34e9dc66c0(0000) GS:ffff89ee64d33000(0000) knlGS:0000000000000000\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  CR2: 00007fe180adef98 CR3: 000000047210e000 CR4: 0000000000350ef0\n  Call Trace:\n   \u003cTASK\u003e\n   kvm_arch_vm_ioctl+0xa72/0x1240 ../arch/x86/kvm/x86.c:7371\n   kvm_vm_ioctl+0x649/0x990 ../virt/kvm/kvm_main.c:5363\n   __se_sys_ioctl+0x101/0x170 ../fs/ioctl.c:51\n   do_syscall_x64 ../arch/x86/entry/syscall_64.c:63 [inline]\n   do_syscall_64+0x6f/0x1f0 ../arch/x86/entry/syscall_64.c:94\n   entry_SYSCALL_64_after_hwframe+0x76/0x7e\n  RIP: 0033:0x7f34e9f7e9a9\n  Code: \u003c48\u003e 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48\n  RSP: 002b:00007f34e9dc6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010\n  RAX: ffffffffffffffda RBX: 00007f34ea1a6080 RCX: 00007f34e9f7e9a9\n  RDX: 0000200000000280 RSI: 000000008010aebb RDI: 0000000000000007\n  RBP: 00007f34ea000d69 R08: 0000000000000000 R09: 0000000000000000\n  R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000\n  R13: 0000000000000000 R14: 00007f34ea1a6080 R15: 00007ffce77197a8\n   \u003c/TASK\u003e\n\nwith a syzlang reproducer that looks like:\n\n  syz_kvm_add_vcpu$x86(0x0, &(0x7f0000000040)={0x0, &(0x7f0000000180)=ANY=[], 0x70}) (async)\n  syz_kvm_add_vcpu$x86(0x0, &(0x7f0000000080)={0x0, &(0x7f0000000180)=ANY=[@ANYBLOB=\"...\"], 0x4f}) (async)\n  r0 = openat$kvm(0xffffffffffffff9c, &(0x7f0000000200), 0x0, 0x0)\n  r1 = ioctl$KVM_CREATE_VM(r0, 0xae01, 0x0)\n  r2 = openat$kvm(0xffffffffffffff9c, &(0x7f0000000240), 0x0, 0x0)\n  r3 = ioctl$KVM_CREATE_VM(r2, 0xae01, 0x0)\n  ioctl$KVM_SET_CLOCK(r3, 0xc008aeba, &(0x7f0000000040)={0x1, 0x8, 0x0, 0x5625e9b0}) (async)\n  ioctl$KVM_SET_PIT2(r3, 0x8010aebb, &(0x7f0000000280)={[...], 0x5}) (async)\n  ioctl$KVM_SET_PIT2(r1, 0x4070aea0, 0x0) (async)\n  r4 = ioctl$KVM_CREATE_VM(0xffffffffffffffff, 0xae01, 0x0)\n  openat$kvm(0xffffffffffffff9c, 0x0, 0x0, 0x0) (async)\n  ioctl$KVM_SET_USER_MEMORY_REGION(r4, 0x4020ae46, &(0x7f0000000400)={0x0, 0x0, 0x0, 0x2000, &(0x7f0000001000/0x2000)=nil}) (async)\n  r5 = ioctl$KVM_CREATE_VCPU(r4, 0xae41, 0x2)\n  close(r0) (async)\n  openat$kvm(0xffffffffffffff9c, &(0x7f0000000000), 0x8000, 0x0) (async)\n  ioctl$KVM_SET_GUEST_DEBUG(r5, 0x4048ae9b, &(0x7f0000000300)={0x4376ea830d46549b, 0x0, [0x46, 0x0, 0x0, 0x0, 0x0, 0x1000]}) (async)\n  ioctl$KVM_RUN(r5, 0xae80, 0x0)\n\nOpportunistically use guard() to avoid having to define a new error label\nand goto usage.","modified":"2026-05-18T05:59:51.790407377Z","published":"2026-04-24T14:42:18.921Z","related":["CGA-qr6c-w2fv-52jm","openSUSE-SU-2026:10703-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31592.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0ff93ff0ba82e9511770e175fa50682a1ab14fb6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/35a0963d361f98bba798fd15d229dcb166c04684"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ab725ac3022469ecd4d7aa7d5646712e98b249d8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b6408b6cec5df76a165575777800ef2aba12b109"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31592.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31592"},{"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":"1e80fdc09d121d8327cdf62eefbb5abadddca792"},{"fixed":"35a0963d361f98bba798fd15d229dcb166c04684"},{"fixed":"ab725ac3022469ecd4d7aa7d5646712e98b249d8"},{"fixed":"0ff93ff0ba82e9511770e175fa50682a1ab14fb6"},{"fixed":"b6408b6cec5df76a165575777800ef2aba12b109"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-31592.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.16.0"},{"fixed":"6.18.24"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.14"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.20.0"},{"fixed":"7.0.1"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-31592.json"}}],"schema_version":"1.7.5"}