{"id":"CVE-2026-23345","summary":"arm64: gcs: Do not set PTE_SHARED on GCS mappings if FEAT_LPA2 is enabled","details":"In the Linux kernel, the following vulnerability has been resolved:\n\narm64: gcs: Do not set PTE_SHARED on GCS mappings if FEAT_LPA2 is enabled\n\nWhen FEAT_LPA2 is enabled, bits 8-9 of the PTE replace the\nshareability attribute with bits 50-51 of the output address. The\n_PAGE_GCS{,_RO} definitions include the PTE_SHARED bits as 0b11 (this\nmatches the other _PAGE_* definitions) but using this macro directly\nleads to the following panic when enabling GCS on a system/model with\nLPA2:\n\n  Unable to handle kernel paging request at virtual address fffff1ffc32d8008\n  Mem abort info:\n    ESR = 0x0000000096000004\n    EC = 0x25: DABT (current EL), IL = 32 bits\n    SET = 0, FnV = 0\n    EA = 0, S1PTW = 0\n    FSC = 0x04: level 0 translation fault\n  Data abort info:\n    ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000\n    CM = 0, WnR = 0, TnD = 0, TagAccess = 0\n    GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0\n  swapper pgtable: 4k pages, 52-bit VAs, pgdp=0000000060f4d000\n  [fffff1ffc32d8008] pgd=100000006184b003, p4d=0000000000000000\n  Internal error: Oops: 0000000096000004 [#1]  SMP\n  CPU: 0 UID: 0 PID: 513 Comm: gcs_write_fault Tainted: G   M                7.0.0-rc1 #1 PREEMPT\n  Tainted: [M]=MACHINE_CHECK\n  Hardware name: QEMU QEMU Virtual Machine, BIOS 2025.02-8+deb13u1 11/08/2025\n  pstate: 03402005 (nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)\n  pc : zap_huge_pmd+0x168/0x468\n  lr : zap_huge_pmd+0x2c/0x468\n  sp : ffff800080beb660\n  x29: ffff800080beb660 x28: fff00000c2058180 x27: ffff800080beb898\n  x26: fff00000c2058180 x25: ffff800080beb820 x24: 00c800010b600f41\n  x23: ffffc1ffc30af1a8 x22: fff00000c2058180 x21: 0000ffff8dc00000\n  x20: fff00000c2bc6370 x19: ffff800080beb898 x18: ffff800080bebb60\n  x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000007\n  x14: 000000000000000a x13: 0000aaaacbbbffff x12: 0000000000000000\n  x11: 0000ffff8ddfffff x10: 00000000000001fe x9 : 0000ffff8ddfffff\n  x8 : 0000ffff8de00000 x7 : 0000ffff8da00000 x6 : fff00000c2bc6370\n  x5 : 0000ffff8da00000 x4 : 000000010b600000 x3 : ffffc1ffc0000000\n  x2 : fff00000c2058180 x1 : fffff1ffc32d8000 x0 : 000000c00010b600\n  Call trace:\n   zap_huge_pmd+0x168/0x468 (P)\n   unmap_page_range+0xd70/0x1560\n   unmap_single_vma+0x48/0x80\n   unmap_vmas+0x90/0x180\n   unmap_region+0x88/0xe4\n   vms_complete_munmap_vmas+0xf8/0x1e0\n   do_vmi_align_munmap+0x158/0x180\n   do_vmi_munmap+0xac/0x160\n   __vm_munmap+0xb0/0x138\n   vm_munmap+0x14/0x20\n   gcs_free+0x70/0x80\n   mm_release+0x1c/0xc8\n   exit_mm_release+0x28/0x38\n   do_exit+0x190/0x8ec\n   do_group_exit+0x34/0x90\n   get_signal+0x794/0x858\n   arch_do_signal_or_restart+0x11c/0x3e0\n   exit_to_user_mode_loop+0x10c/0x17c\n   el0_da+0x8c/0x9c\n   el0t_64_sync_handler+0xd0/0xf0\n   el0t_64_sync+0x198/0x19c\n  Code: aa1603e2 d34cfc00 cb813001 8b011861 (f9400420)\n\nSimilarly to how the kernel handles protection_map[], use a\ngcs_page_prot variable to store the protection bits and clear PTE_SHARED\nif LPA2 is enabled.\n\nAlso remove the unused PAGE_GCS{,_RO} macros.","modified":"2026-04-02T13:12:22.852931Z","published":"2026-03-25T10:27:32.432Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23345.json","cna_assigner":"Linux"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1df3ef7e612d6ccbae5a48e1121553c47c2123d6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8a85b3131225a8c8143ba2ae29c0eef8c1f9117f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ca1684dd297bf0725c1d487cff80e615497accf6"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23345.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23345"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6497b66ba6945f142902c7e8fce86e47016ead1c"},{"fixed":"ca1684dd297bf0725c1d487cff80e615497accf6"},{"fixed":"1df3ef7e612d6ccbae5a48e1121553c47c2123d6"},{"fixed":"8a85b3131225a8c8143ba2ae29c0eef8c1f9117f"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-23345.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.17"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.7"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-23345.json"}}],"schema_version":"1.7.5"}