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| author |   Quentin Perret <qperret@google.com> | 2025-02-13 15:36:14 +0000 |
|---|---|---|
| committer |   Marc Zyngier <maz@kernel.org> | 2025-02-13 17:57:27 +0000 |
| commit | b938731ed2d4eea8e268a27bfc600581fedae2a9 (patch) | |
| tree | 51f03a7fb0c8fd13a2c27783dfc1e9b6b8fe8f59 | |
| parent | KVM: arm64: Convert timer offset VA when accessed in HYP code (diff) | |
| download | wireguard-linux-b938731ed2d4eea8e268a27bfc600581fedae2a9.tar.xz wireguard-linux-b938731ed2d4eea8e268a27bfc600581fedae2a9.zip | |
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 <ben.simner@cl.cam.ac.uk>
Signed-off-by: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20250213153615.3642515-1-qperret@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
| -rw-r--r-- | arch/arm64/include/asm/kvm_host.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index c77acc990457..3a7ec98ef123 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; |