Commit c0e296f2 authored by Stanislav Kinsburskii's avatar Stanislav Kinsburskii Committed by Wei Liu
Browse files

mshv: Fix error handling in mshv_region_pin 



The current error handling has two issues:

First, pin_user_pages_fast() can return a short pin count (less than
requested but greater than zero) when it cannot pin all requested pages.
This is treated as success, leading to partially pinned regions being
used, which causes memory corruption.

Second, when an error occurs mid-loop, already pinned pages from the
current batch are not properly accounted for before calling
mshv_region_invalidate_pages(), causing a page reference leak.

Treat short pins as errors and fix partial batch accounting before
cleanup.

Signed-off-by: default avatarStanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Reviewed-by: default avatarMichael Kelley <mhklinux@outlook.com>
Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
parent b2ae73d9

drivers/hv/mshv_regions.c

+4 −2
Original line number Diff line number Diff line
@@ -314,15 +314,17 @@ int mshv_region_pin(struct mshv_mem_region *region) 
		ret = pin_user_pages_fast(userspace_addr, nr_pages,

					  FOLL_WRITE | FOLL_LONGTERM,

					  pages);

		if (ret < 0)

		if (ret != nr_pages)

			goto release_pages;

	}



	return 0;



release_pages:

	if (ret > 0)

		done_count += ret;

	mshv_region_invalidate_pages(region, 0, done_count);

	return ret;

	return ret < 0 ? ret : -ENOMEM;

}



static int mshv_region_chunk_unmap(struct mshv_mem_region *region,