linux-kernel - [PATCH 1/5] vfio/type1: Catch zero from pin_user_pages

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Message-ID: <20250205231728.2527186-2-alex.williamson@redhat.com>
Date: Wed,  5 Feb 2025 16:17:17 -0700
From: Alex Williamson <alex.williamson@...hat.com>
To: alex.williamson@...hat.com
Cc: kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	peterx@...hat.com,
	mitchell.augustin@...onical.com,
	clg@...hat.com
Subject: [PATCH 1/5] vfio/type1: Catch zero from pin_user_pages_remote()

pin_user_pages_remote() can currently return zero for invalid args
or zero nr_pages, neither of which should ever happen.  However
vaddr_get_pfns() indicates it should only ever return a positive
value or -errno and there's a theoretical case where this can slip
through and be unhandled by callers.  Therefore convert zero to
-EFAULT.

Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
---
 drivers/vfio/vfio_iommu_type1.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 50ebc9593c9d..119cf886d8c0 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -564,6 +564,8 @@ static int vaddr_get_pfns(struct mm_struct *mm, unsigned long vaddr,
 	if (ret > 0) {
 		*pfn = page_to_pfn(pages[0]);
 		goto done;
+	} else if (!ret) {
+		ret = -EFAULT;
 	}
 
 	vaddr = untagged_addr_remote(mm, vaddr);
-- 
2.47.1