linux-kernel - [PATCH] drm/nouveau/mmu: fix potential overflow in PFN size calculation

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Message-ID: <20250523075015.884716-1-sdl@nppct.ru>
Date: Fri, 23 May 2025 07:50:14 +0000
From: Alexey Nepomnyashih <sdl@...ct.ru>
To: Lyude Paul <lyude@...hat.com>
Cc: Alexey Nepomnyashih <sdl@...ct.ru>,
	Danilo Krummrich <dakr@...nel.org>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	dri-devel@...ts.freedesktop.org,
	nouveau@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	lvc-project@...uxtesting.org,
	stable@...r.kernel.org
Subject: [PATCH] drm/nouveau/mmu: fix potential overflow in PFN size calculation

On most Linux-supported platforms, `int` is 32-bit, making (1 << 47)
undefined and potentially dangerous. To ensure defined behavior and
correct 64-bit arithmetic, replace `1` with `1ULL`.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Cc: stable@...r.kernel.org # v5.1+
Fixes: a5ff307fe1f2 ("drm/nouveau/mmu: add a privileged method to directly manage PTEs")
Signed-off-by: Alexey Nepomnyashih <sdl@...ct.ru>
---
 drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
index 9c97800fe037..29da1acbe3a8 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
@@ -1383,7 +1383,7 @@ nvkm_vmm_pfn_map(struct nvkm_vmm *vmm, u8 shift, u64 addr, u64 size, u64 *pfn)
 			 */
 			while (size) {
 				pfn[pi++] = NVKM_VMM_PFN_NONE;
-				size -= 1 << page->shift;
+				size -= 1ULL << page->shift;
 			}
 		} else {
 			pi += size >> page->shift;
-- 
2.43.0