CVE-2026-63875

Summary

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

arm64: tlb: Flush walk cache when unsharing PMD tables

When huge_pmd_unshare() is called to unshare a PMD table, the tlb_unshare_pmd_ptdesc() function sets tlb->unshared_tables=true but the aarch64 tlb_flush() only checked tlb->freed_tables to determine whether to use TLBF_NONE (vae1is, invalidates walk cache) or TLBF_NOWALKCACHE (vale1is, leaf-only).

This caused the stale PMD page table entry to remain in the walk cache after unshare, potentially leading to incorrect page table walks.

Fix by including unshared_tables in the check, so that when unsharing tables, TLBF_NONE is used and the walk cache is properly invalidated.

Here is the detailed distinction between vae1is and vale1is:

Instruction CombinationActual Invalidation Scope
VAE1IS + TTL=0All entries at all levels (full invalidation)
VAE1IS + TTL=2 (L2)Non-leaf at Level 0/1 + leaf at Level 2
VALE1IS + TTL=0Leaf entries at all levels (non-leaf not cleared)
VALE1IS + TTL=2 (L2)Leaf entry at Level 2 only

Affected Software

VendorProductVersion RangeStatus
LinuxLinux6495204f8219a57859669d618b25d06176d5a872 < dced308d7d6a0de1c09d2058f38f1aaaf5cbb914affected
LinuxLinuxce4cf24761467756462c0e1dbe4a5e9c9eb520fc < 47490bbb05c8c0e09cc3cfd237d8934ffc340583affected
LinuxLinuxdaa6707b71a2da23a82979fa21f788aeb706f1a2 < 0199c9d57861f17b556b6cba1f765c7cce79745baffected
LinuxLinuxff37dd18ce7739a26aab0cc2d31006a45e6bde63 < d766a49d9b55705c4737cd8bb5d3faa2d31330fdaffected
LinuxLinuxda06bb0ca45b1ca6f1ab55023e34e61a520337f3 < 8ca7284da0e67b3e71d90ec17f08286774245ad9affected
LinuxLinux9b671f6f432be07c0ddd66e437d6d0e0db684f83 < fe93e907b1af03cc229a80aa64a570a103d2b279affected
LinuxLinux8ce720d5bd91e9dc16db3604aa4b1bf76770a9a1 < 48125cd9c55cbe297b59fd1f9bda48b0960bd181affected
LinuxLinux8ce720d5bd91e9dc16db3604aa4b1bf76770a9a1 < c2ff4764e03e7a8d758352f4aceb8fe1be6ac971affected
LinuxLinux5.10.253 < 5.10.259affected
LinuxLinux5.15.203 < 5.15.210affected
LinuxLinux6.1.167 < 6.1.176affected
LinuxLinux6.6.127 < 6.6.143affected
LinuxLinux6.12.74 < 6.12.93affected
LinuxLinux6.18.13 < 6.18.35affected
LinuxLinux6.19affected
LinuxLinux0 < 6.19unaffected
LinuxLinux5.10.259 <= 5.10.*unaffected
LinuxLinux5.15.210 <= 5.15.*unaffected
LinuxLinux6.1.176 <= 6.1.*unaffected
LinuxLinux6.6.143 <= 6.6.*unaffected
LinuxLinux6.12.93 <= 6.12.*unaffected
LinuxLinux6.18.35 <= 6.18.*unaffected
LinuxLinux7.0.12 <= 7.0.*unaffected
LinuxLinux7.1 <= *unaffected

Weaknesses

References