linux/arch/s390/mm
David Hildenbrand 1493e0f944 KVM: s390: vsie: Fix possible race when shadowing region 3 tables
We have to properly retry again by returning -EINVAL immediately in case
somebody else instantiated the table concurrently. We missed to add the
goto in this function only. The code now matches the other, similar
shadowing functions.

We are overwriting an existing region 2 table entry. All allocated pages
are added to the crst_list to be freed later, so they are not lost
forever. However, when unshadowing the region 2 table, we wouldn't trigger
unshadowing of the original shadowed region 3 table that we replaced. It
would get unshadowed when the original region 3 table is modified. As it's
not connected to the page table hierarchy anymore, it's not going to get
used anymore. However, for a limited time, this page table will stick
around, so it's in some sense a temporary memory leak.

Identified by manual code inspection. I don't think this classifies as
stable material.

Fixes: 998f637cc4 ("s390/mm: avoid races on region/segment/page table shadowing")
Signed-off-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20200403153050.20569-4-david@redhat.com
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
2020-04-07 13:12:38 +02:00
..
cmm.c s390/cmm: fix information leak in cmm_timeout_handler() 2019-10-31 17:26:48 +01:00
dump_pagetables.c s390/mm: fix dump_pagetables top level page table walking 2019-08-06 13:58:34 +02:00
extmem.c s390/extmem: use refcount_t for refcount 2019-08-21 12:41:43 +02:00
fault.c ARM: 2020-04-02 15:13:15 -07:00
gmap.c KVM: s390: vsie: Fix possible race when shadowing region 3 tables 2020-04-07 13:12:38 +02:00
hugetlbpage.c s390/mm: fix dynamic pagetable upgrade for hugetlbfs 2020-01-30 13:07:54 +01:00
init.c mm/memory_hotplug: shrink zones when offlining memory 2020-01-04 13:55:08 -08:00
kasan_init.c s390/kasan: add KASAN_VMALLOC support 2019-12-11 19:56:59 +01:00
maccess.c s390: disable preemption when switching to nodat stack with CALL_ON_STACK 2019-11-30 10:52:45 +01:00
Makefile s390/mm: convert to the generic get_user_pages_fast code 2019-04-23 16:30:04 +02:00
mmap.c s390/mm: mmap base does not depend on ADDR_NO_RANDOMIZE personality 2019-06-04 15:03:53 +02:00
page-states.c s390/cmma: reuse kstrtobool for option value parsing 2019-08-26 12:51:18 +02:00
pageattr.c s390/mm: Clear huge page storage keys on enable_skey 2018-07-30 11:20:18 +01:00
pgalloc.c mm: treewide: clarify pgtable_page_{ctor,dtor}() naming 2019-09-26 10:10:44 -07:00
pgtable.c s390/mm: silence compiler warning when compiling without CONFIG_PGSTE 2019-04-10 17:48:28 +02:00
vmem.c s390/kernel: introduce .dma sections 2019-04-29 10:47:10 +02:00