From: Quentin Perret Date: Thu, 13 Feb 2025 15:36:14 +0000 (+0000) Subject: KVM: arm64: Fix alignment of kvm_hyp_memcache allocations X-Git-Tag: v6.14-rc3~9^2~4^2~2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b938731ed2d4eea8e268a27bfc600581fedae2a9;p=thirdparty%2Flinux.git KVM: arm64: Fix alignment of kvm_hyp_memcache allocations When allocating guest stage-2 page-table pages at EL2, pKVM can consume pages from the host-provided kvm_hyp_memcache. As pgtable.c expects zeroed pages, guest_s2_zalloc_page() actively implements this zeroing with a PAGE_SIZE memset. Unfortunately, we don't check the page alignment of the host-provided address before doing so, which could lead to the memset overrunning the page if the host was malicious. Fix this by simply force-aligning all kvm_hyp_memcache allocations to page boundaries. Fixes: 60dfe093ec13 ("KVM: arm64: Instantiate guest stage-2 page-tables at EL2") Reported-by: Ben Simner Signed-off-by: Quentin Perret Link: https://lore.kernel.org/r/20250213153615.3642515-1-qperret@google.com Signed-off-by: Marc Zyngier --- diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index c77acc9904576..3a7ec98ef1238 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -100,7 +100,7 @@ static inline void push_hyp_memcache(struct kvm_hyp_memcache *mc, static inline void *pop_hyp_memcache(struct kvm_hyp_memcache *mc, void *(*to_va)(phys_addr_t phys)) { - phys_addr_t *p = to_va(mc->head); + phys_addr_t *p = to_va(mc->head & PAGE_MASK); if (!mc->nr_pages) return NULL;