Commit ba9eb9b8 authored by Nuno Das Neves's avatar Nuno Das Neves Committed by Wei Liu
Browse files

mshv: Fix create memory region overlap check 



The current check is incorrect; it only checks if the beginning or end
of a region is within an existing region. This doesn't account for
userspace specifying a region that begins before and ends after an
existing region.

Change the logic to a range intersection check against gfns and uaddrs
for each region.

Remove mshv_partition_region_by_uaddr() as it is no longer used.

Fixes: 621191d7 ("Drivers: hv: Introduce mshv_root module to expose /dev/mshv to VMMs")
Reported-by: default avatarMichael Kelley <mhklinux@outlook.com>
Closes: https://lore.kernel.org/linux-hyperv/SN6PR02MB41575BE0406D3AB22E1D7DB5D4C2A@SN6PR02MB4157.namprd02.prod.outlook.com/


Signed-off-by: default avatarNuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: default avatarMichael Kelley <mhklinux@outlook.com>
Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
parent 8ec6070f

drivers/hv/mshv_root_main.c

+11 −20
Original line number Diff line number Diff line
@@ -1174,21 +1174,6 @@ mshv_partition_region_by_gfn(struct mshv_partition *partition, u64 gfn) 
	return NULL;

}



static struct mshv_mem_region *

mshv_partition_region_by_uaddr(struct mshv_partition *partition, u64 uaddr)

{

	struct mshv_mem_region *region;



	hlist_for_each_entry(region, &partition->pt_mem_regions, hnode) {

		if (uaddr >= region->start_uaddr &&

		    uaddr < region->start_uaddr +

			    (region->nr_pages << HV_HYP_PAGE_SHIFT))

			return region;

	}



	return NULL;

}



/*

 * NB: caller checks and makes sure mem->size is page aligned

 * Returns: 0 with regionpp updated on success, or -errno
@@ -1198,15 +1183,21 @@ static int mshv_partition_create_region(struct mshv_partition *partition, 
					struct mshv_mem_region **regionpp,

					bool is_mmio)

{

	struct mshv_mem_region *region;

	struct mshv_mem_region *region, *rg;

	u64 nr_pages = HVPFN_DOWN(mem->size);



	/* Reject overlapping regions */

	if (mshv_partition_region_by_gfn(partition, mem->guest_pfn) ||

	    mshv_partition_region_by_gfn(partition, mem->guest_pfn + nr_pages - 1) ||

	    mshv_partition_region_by_uaddr(partition, mem->userspace_addr) ||

	    mshv_partition_region_by_uaddr(partition, mem->userspace_addr + mem->size - 1))

	hlist_for_each_entry(rg, &partition->pt_mem_regions, hnode) {

		u64 rg_size = rg->nr_pages << HV_HYP_PAGE_SHIFT;



		if ((mem->guest_pfn + nr_pages <= rg->start_gfn ||

		     rg->start_gfn + rg->nr_pages <= mem->guest_pfn) &&

		    (mem->userspace_addr + mem->size <= rg->start_uaddr ||

		     rg->start_uaddr + rg_size <= mem->userspace_addr))

			continue;



		return -EEXIST;

	}



	region = vzalloc(sizeof(*region) + sizeof(struct page *) * nr_pages);

	if (!region)