From 8a3caa6d74597c2a083f7c87f866891a0b12540b Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Mon, 18 Nov 2013 10:35:55 +0100 Subject: KVM: kvm_clear_guest_page(): fix empty_zero_page usage Using the address of 'empty_zero_page' as source address in order to clear a page is wrong. On some architectures empty_zero_page is only the pointer to the struct page of the empty_zero_page. Therefore the clear page operation would copy the contents of a couple of struct pages instead of clearing a page. For kvm only arm/arm64 are affected by this bug. To fix this use the ZERO_PAGE macro instead which will return the struct page address of the empty_zero_page on all architectures. Signed-off-by: Heiko Carstens Signed-off-by: Gleb Natapov --- virt/kvm/kvm_main.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'virt/kvm') diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 662f34c3287e..a0aa84b5941a 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1615,8 +1615,9 @@ EXPORT_SYMBOL_GPL(kvm_read_guest_cached); int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len) { - return kvm_write_guest_page(kvm, gfn, (const void *) empty_zero_page, - offset, len); + const void *zero_page = (const void *) __va(page_to_phys(ZERO_PAGE(0))); + + return kvm_write_guest_page(kvm, gfn, zero_page, offset, len); } EXPORT_SYMBOL_GPL(kvm_clear_guest_page); -- cgit v1.2.2 From 338c7dbadd2671189cec7faf64c84d01071b3f96 Mon Sep 17 00:00:00 2001 From: Andy Honig Date: Mon, 18 Nov 2013 16:09:22 -0800 Subject: KVM: Improve create VCPU parameter (CVE-2013-4587) In multiple functions the vcpu_id is used as an offset into a bitfield. Ag malicious user could specify a vcpu_id greater than 255 in order to set or clear bits in kernel memory. This could be used to elevate priveges in the kernel. This patch verifies that the vcpu_id provided is less than 255. The api documentation already specifies that the vcpu_id must be less than max_vcpus, but this is currently not checked. Reported-by: Andrew Honig Cc: stable@vger.kernel.org Signed-off-by: Andrew Honig Signed-off-by: Paolo Bonzini --- virt/kvm/kvm_main.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'virt/kvm') diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index a0aa84b5941a..4f588bc94186 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1898,6 +1898,9 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id) int r; struct kvm_vcpu *vcpu, *v; + if (id >= KVM_MAX_VCPUS) + return -EINVAL; + vcpu = kvm_arch_vcpu_create(kvm, id); if (IS_ERR(vcpu)) return PTR_ERR(vcpu); -- cgit v1.2.2