From 13a17cc0526f08d1df9507f7484176371cd263a0 Mon Sep 17 00:00:00 2001 From: Igor Mammedov Date: Wed, 11 Sep 2019 03:52:18 -0400 Subject: KVM: s390: kvm_s390_vm_start_migration: check dirty_bitmap before using it as target for memset() If userspace doesn't set KVM_MEM_LOG_DIRTY_PAGES on memslot before calling kvm_s390_vm_start_migration(), kernel will oops with: Unable to handle kernel pointer dereference in virtual kernel address space Failing address: 0000000000000000 TEID: 0000000000000483 Fault in home space mode while using kernel ASCE. AS:0000000002a2000b R2:00000001bff8c00b R3:00000001bff88007 S:00000001bff91000 P:000000000000003d Oops: 0004 ilc:2 [#1] SMP ... Call Trace: ([<001fffff804ec552>] kvm_s390_vm_set_attr+0x347a/0x3828 [kvm]) [<001fffff804ecfc0>] kvm_arch_vm_ioctl+0x6c0/0x1998 [kvm] [<001fffff804b67e4>] kvm_vm_ioctl+0x51c/0x11a8 [kvm] [<00000000008ba572>] do_vfs_ioctl+0x1d2/0xe58 [<00000000008bb284>] ksys_ioctl+0x8c/0xb8 [<00000000008bb2e2>] sys_ioctl+0x32/0x40 [<000000000175552c>] system_call+0x2b8/0x2d8 INFO: lockdep is turned off. Last Breaking-Event-Address: [<0000000000dbaf60>] __memset+0xc/0xa0 due to ms->dirty_bitmap being NULL, which might crash the host. Make sure that ms->dirty_bitmap is set before using it or return -EINVAL otherwise. Cc: Fixes: afdad61615cc ("KVM: s390: Fix storage attributes migration with memory slots") Signed-off-by: Igor Mammedov Link: https://lore.kernel.org/kvm/20190911075218.29153-1-imammedo@redhat.com/ Reviewed-by: David Hildenbrand Reviewed-by: Christian Borntraeger Reviewed-by: Claudio Imbrenda Reviewed-by: Cornelia Huck Reviewed-by: Janosch Frank Signed-off-by: Janosch Frank Signed-off-by: Christian Borntraeger --- arch/s390/kvm/kvm-s390.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 3f520cd837fb..b298fcc9ec56 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -1018,6 +1018,8 @@ static int kvm_s390_vm_start_migration(struct kvm *kvm) /* mark all the pages in active slots as dirty */ for (slotnr = 0; slotnr < slots->used_slots; slotnr++) { ms = slots->memslots + slotnr; + if (!ms->dirty_bitmap) + return -EINVAL; /* * The second half of the bitmap is only used on x86, * and would be wasted otherwise, so we put it to good -- cgit From 53936b5bf35e140ae27e4bbf0447a61063f400da Mon Sep 17 00:00:00 2001 From: Thomas Huth Date: Thu, 12 Sep 2019 13:54:38 +0200 Subject: KVM: s390: Do not leak kernel stack data in the KVM_S390_INTERRUPT ioctl When the userspace program runs the KVM_S390_INTERRUPT ioctl to inject an interrupt, we convert them from the legacy struct kvm_s390_interrupt to the new struct kvm_s390_irq via the s390int_to_s390irq() function. However, this function does not take care of all types of interrupts that we can inject into the guest later (see do_inject_vcpu()). Since we do not clear out the s390irq values before calling s390int_to_s390irq(), there is a chance that we copy random data from the kernel stack which could be leaked to the userspace later. Specifically, the problem exists with the KVM_S390_INT_PFAULT_INIT interrupt: s390int_to_s390irq() does not handle it, and the function __inject_pfault_init() later copies irq->u.ext which contains the random kernel stack data. This data can then be leaked either to the guest memory in __deliver_pfault_init(), or the userspace might retrieve it directly with the KVM_S390_GET_IRQ_STATE ioctl. Fix it by handling that interrupt type in s390int_to_s390irq(), too, and by making sure that the s390irq struct is properly pre-initialized. And while we're at it, make sure that s390int_to_s390irq() now directly returns -EINVAL for unknown interrupt types, so that we immediately get a proper error code in case we add more interrupt types to do_inject_vcpu() without updating s390int_to_s390irq() sometime in the future. Cc: stable@vger.kernel.org Reviewed-by: David Hildenbrand Reviewed-by: Christian Borntraeger Reviewed-by: Janosch Frank Signed-off-by: Thomas Huth Link: https://lore.kernel.org/kvm/20190912115438.25761-1-thuth@redhat.com Signed-off-by: Christian Borntraeger --- arch/s390/kvm/interrupt.c | 10 ++++++++++ arch/s390/kvm/kvm-s390.c | 2 +- 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index b5fd6e85657c..d1ccc168c071 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -1961,6 +1961,16 @@ int s390int_to_s390irq(struct kvm_s390_interrupt *s390int, case KVM_S390_MCHK: irq->u.mchk.mcic = s390int->parm64; break; + case KVM_S390_INT_PFAULT_INIT: + irq->u.ext.ext_params = s390int->parm; + irq->u.ext.ext_params2 = s390int->parm64; + break; + case KVM_S390_RESTART: + case KVM_S390_INT_CLOCK_COMP: + case KVM_S390_INT_CPU_TIMER: + break; + default: + return -EINVAL; } return 0; } diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index b298fcc9ec56..0d697b436f2b 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -4335,7 +4335,7 @@ long kvm_arch_vcpu_async_ioctl(struct file *filp, } case KVM_S390_INTERRUPT: { struct kvm_s390_interrupt s390int; - struct kvm_s390_irq s390irq; + struct kvm_s390_irq s390irq = {}; if (copy_from_user(&s390int, argp, sizeof(s390int))) return -EFAULT; -- cgit