| Message ID | 20190911075218.29153-1-imammedo@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] KVM: s390: kvm_s390_vm_start_migration: check dirty_bitmap before using it as target for memset() | expand |
On 11.09.19 09:52, Igor Mammedov wrote: > 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 -ENIVAL otherwise. s/ENIVAL/EINVAL/ I assume Christian can fix that up when applying. > > Fixes: afdad61615cc ("KVM: s390: Fix storage attributes migration with memory slots") > Signed-off-by: Igor Mammedov <imammedo@redhat.com> > --- > Cc: stable@vger.kernel.org # v4.19+ > > v2: > - remove not true anym 'warning' clause in commit message > v2: > - drop WARN() > > 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 f329dcb3f44c..2a40cd3e40b4 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 > You should keep the RB's, especially when only rephrasing the commit message ;) Reviewed-by: David Hildenbrand <david@redhat.com>
On 9/11/19 9:52 AM, Igor Mammedov wrote: > 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 -ENIVAL otherwise. Fixed that while picking and added my reviewed-by, as well as the others you removed. Thanks for your patch.
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index f329dcb3f44c..2a40cd3e40b4 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
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 -ENIVAL otherwise. Fixes: afdad61615cc ("KVM: s390: Fix storage attributes migration with memory slots") Signed-off-by: Igor Mammedov <imammedo@redhat.com> --- Cc: stable@vger.kernel.org # v4.19+ v2: - remove not true anym 'warning' clause in commit message v2: - drop WARN() arch/s390/kvm/kvm-s390.c | 2 ++ 1 file changed, 2 insertions(+)