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authorIgor Mammedov <imammedo@redhat.com>2019-09-11 03:52:18 -0400
committerChristian Borntraeger <borntraeger@de.ibm.com>2019-09-12 13:09:17 +0200
commit13a17cc0526f08d1df9507f7484176371cd263a0 (patch)
treec3d7bf2eda08fb3a614ae05c4731f4ac444641d8
parent609488bc979f99f805f34e9a32c1e3b71179d10b (diff)
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: <stable@vger.kernel.org> Fixes: afdad61615cc ("KVM: s390: Fix storage attributes migration with memory slots") Signed-off-by: Igor Mammedov <imammedo@redhat.com> Link: https://lore.kernel.org/kvm/20190911075218.29153-1-imammedo@redhat.com/ Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Reviewed-by: Cornelia Huck <cohuck@redhat.com> Reviewed-by: Janosch Frank <frankja@linux.ibm.com> Signed-off-by: Janosch Frank <frankja@linux.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
-rw-r--r--arch/s390/kvm/kvm-s390.c2
1 files changed, 2 insertions, 0 deletions
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