]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
hugetlbfs: don't access uninitialized memmaps in pfn_range_valid_gigantic()
authorDavid Hildenbrand <david@redhat.com>
Sat, 19 Oct 2019 03:20:05 +0000 (20:20 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sat, 19 Oct 2019 10:32:32 +0000 (06:32 -0400)
commitf231fe4235e22e18d847e05cbe705deaca56580a
tree094a1cff442b6fa47009c945af69c99148a4b63d
parentf3057ad767542be7bbac44e548cb44017178a163
hugetlbfs: don't access uninitialized memmaps in pfn_range_valid_gigantic()

Uninitialized memmaps contain garbage and in the worst case trigger
kernel BUGs, especially with CONFIG_PAGE_POISONING.  They should not get
touched.

Let's make sure that we only consider online memory (managed by the
buddy) that has initialized memmaps.  ZONE_DEVICE is not applicable.

page_zone() will call page_to_nid(), which will trigger
VM_BUG_ON_PGFLAGS(PagePoisoned(page), page) with CONFIG_PAGE_POISONING
and CONFIG_DEBUG_VM_PGFLAGS when called on uninitialized memmaps.  This
can be the case when an offline memory block (e.g., never onlined) is
spanned by a zone.

Note: As explained by Michal in [1], alloc_contig_range() will verify
the range.  So it boils down to the wrong access in this function.

[1] http://lkml.kernel.org/r/20180423000943.GO17484@dhcp22.suse.cz

Link: http://lkml.kernel.org/r/20191015120717.4858-1-david@redhat.com
Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") [visible after d0dc12e86b319]
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: Michal Hocko <mhocko@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: <stable@vger.kernel.org> [4.13+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/hugetlb.c