6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Stanislav Kinsburskii [ Upstream commit c0e296f257671ba10249630fe58026f29e4804d9 ] 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: Stanislav Kinsburskii Reviewed-by: Michael Kelley Signed-off-by: Wei Liu Signed-off-by: Sasha Levin --- drivers/hv/mshv_regions.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/hv/mshv_regions.c b/drivers/hv/mshv_regions.c index 35b866670840e..5372b7ec1871a 100644 --- a/drivers/hv/mshv_regions.c +++ b/drivers/hv/mshv_regions.c @@ -130,7 +130,7 @@ 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; } @@ -140,8 +140,10 @@ int mshv_region_pin(struct mshv_mem_region *region) 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; } void mshv_region_destroy(struct mshv_mem_region *region) -- 2.53.0