CVE-2026-23345

In the Linux kernel, the following vulnerability has been resolved:

arm64: gcs: Do not set PTESHARED on GCS mappings if FEATLPA2 is enabled

When FEAT_LPA2 is enabled, bits 8-9 of the PTE replace the shareability attribute with bits 50-51 of the output address. The PAGEGCS{,RO} definitions include the PTESHARED bits as 0b11 (this matches the other PAGE* definitions) but using this macro directly leads to the following panic when enabling GCS on a system/model with LPA2:

Unable to handle kernel paging request at virtual address fffff1ffc32d8008 Mem abort info: ESR = 0x0000000096000004 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x04: level 0 translation fault Data abort info: ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 CM = 0, WnR = 0, TnD = 0, TagAccess = 0 GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 swapper pgtable: 4k pages, 52-bit VAs, pgdp=0000000060f4d000 [fffff1ffc32d8008] pgd=100000006184b003, p4d=0000000000000000 Internal error: Oops: 0000000096000004 [#1] SMP CPU: 0 UID: 0 PID: 513 Comm: gcswritefault Tainted: G M 7.0.0-rc1 #1 PREEMPT Tainted: [M]=MACHINECHECK Hardware name: QEMU QEMU Virtual Machine, BIOS 2025.02-8+deb13u1 11/08/2025 pstate: 03402005 (nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) pc : zaphugepmd+0x168/0x468 lr : zaphugepmd+0x2c/0x468 sp : ffff800080beb660 x29: ffff800080beb660 x28: fff00000c2058180 x27: ffff800080beb898 x26: fff00000c2058180 x25: ffff800080beb820 x24: 00c800010b600f41 x23: ffffc1ffc30af1a8 x22: fff00000c2058180 x21: 0000ffff8dc00000 x20: fff00000c2bc6370 x19: ffff800080beb898 x18: ffff800080bebb60 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000007 x14: 000000000000000a x13: 0000aaaacbbbffff x12: 0000000000000000 x11: 0000ffff8ddfffff x10: 00000000000001fe x9 : 0000ffff8ddfffff x8 : 0000ffff8de00000 x7 : 0000ffff8da00000 x6 : fff00000c2bc6370 x5 : 0000ffff8da00000 x4 : 000000010b600000 x3 : ffffc1ffc0000000 x2 : fff00000c2058180 x1 : fffff1ffc32d8000 x0 : 000000c00010b600 Call trace: zaphugepmd+0x168/0x468 (P) unmappagerange+0xd70/0x1560 unmapsinglevma+0x48/0x80 unmapvmas+0x90/0x180 unmapregion+0x88/0xe4 vmscompletemunmapvmas+0xf8/0x1e0 dovmialignmunmap+0x158/0x180 dovmi_munmap+0xac/0x160 __vmmunmap+0xb0/0x138 vmmunmap+0x14/0x20 gcsfree+0x70/0x80 mmrelease+0x1c/0xc8 exitmmrelease+0x28/0x38 doexit+0x190/0x8ec dogroupexit+0x34/0x90 getsignal+0x794/0x858 archdosignalorrestart+0x11c/0x3e0 exittousermodeloop+0x10c/0x17c el0da+0x8c/0x9c el0t64synchandler+0xd0/0xf0 el0t64sync+0x198/0x19c Code: aa1603e2 d34cfc00 cb813001 8b011861 (f9400420)

Similarly to how the kernel handles protectionmap[], use a gcspageprot variable to store the protection bits and clear PTESHARED if LPA2 is enabled.

Also remove the unused PAGE_GCS{,_RO} macros.