From fd948c3f96b18ff9ba7d3e8eae13d196593e1aaf Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Carlos=20L=C3=B3pez?= Date: Tue, 12 May 2026 12:00:42 +0200 Subject: [PATCH] virt: sev-guest: Explicitly leak pages in unknown state MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When set_memory_{encrypted,decrypted}() fail, the user cannot know at which point the function failed, meaning that the pages are left in an unknown state from the point of view of the caller. Since the pages may be left in an unencrypted state, they are not suitable for general use, and cannot be returned safely to the buddy allocator. Avoid the issue by never freeing the pages, and then do the proper accounting by calling snp_leak_pages(). Fixes: 3e385c0d6ce8 ("virt: sev-guest: Move SNP Guest Request data pages handling under snp_cmd_mutex") Signed-off-by: Carlos López Signed-off-by: Borislav Petkov (AMD) Cc: stable@kernel.org --- drivers/virt/coco/sev-guest/sev-guest.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index 910a1de0d5a7..d186ae55cf63 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -176,6 +176,7 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques struct snp_guest_req req = {}; int ret, npages = 0, resp_len; sockptr_t certs_address; + u64 pfn; if (sockptr_is_null(io->req_data) || sockptr_is_null(io->resp_data)) return -EINVAL; @@ -215,10 +216,11 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques if (!req.certs_data) return -ENOMEM; + pfn = PHYS_PFN(virt_to_phys(req.certs_data)); ret = set_memory_decrypted((unsigned long)req.certs_data, npages); if (ret) { pr_err("failed to mark page shared, ret=%d\n", ret); - free_pages_exact(req.certs_data, npages << PAGE_SHIFT); + snp_leak_pages(pfn, npages); return -EFAULT; } @@ -272,10 +274,12 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques kfree(report_resp); e_free_data: if (npages) { - if (set_memory_encrypted((unsigned long)req.certs_data, npages)) + if (set_memory_encrypted((unsigned long)req.certs_data, npages)) { WARN_ONCE(ret, "failed to restore encryption mask (leak it)\n"); - else + snp_leak_pages(pfn, npages); + } else { free_pages_exact(req.certs_data, npages << PAGE_SHIFT); + } } return ret; }