From: Kees Cook <keescook@chromium.org>
To: linux-hardening@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>,
nouveau@lists.freedesktop.org,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
Ben Skeggs <bskeggs@redhat.com>, Daniel Vetter <daniel@ffwll.ch>,
Justin Stitt <justinstitt@google.com>,
Dave Airlie <airlied@redhat.com>,
Bill Wendling <morbo@google.com>
Subject: [PATCH 48/82] drm/nouveau/mmu: Refactor intentional wrap-around test
Date: Mon, 22 Jan 2024 16:27:23 -0800 [thread overview]
Message-ID: <20240123002814.1396804-48-keescook@chromium.org> (raw)
In-Reply-To: <20240122235208.work.748-kees@kernel.org>
In an effort to separate intentional arithmetic wrap-around from
unexpected wrap-around, we need to refactor places that depend on this
kind of math. One of the most common code patterns of this is:
VAR + value < VAR
Notably, this is considered "undefined behavior" for signed and pointer
types, which the kernel works around by using the -fno-strict-overflow
option in the build[1] (which used to just be -fwrapv). Regardless, we
want to get the kernel source to the position where we can meaningfully
instrument arithmetic wrap-around conditions and catch them when they
are unexpected, regardless of whether they are signed[2], unsigned[3],
or pointer[4] types.
Refactor open-coded wrap-around addition test to use add_would_overflow().
This paves the way to enabling the wrap-around sanitizers in the future.
Link: https://git.kernel.org/linus/68df3755e383e6fecf2354a67b08f92f18536594 [1]
Link: https://github.com/KSPP/linux/issues/26 [2]
Link: https://github.com/KSPP/linux/issues/27 [3]
Link: https://github.com/KSPP/linux/issues/344 [4]
Cc: Karol Herbst <kherbst@redhat.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Danilo Krummrich <dakr@redhat.com>
Cc: David Airlie <airlied@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Cc: nouveau@lists.freedesktop.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
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 6ca1a82ccbc1..87c0903be9a7 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
@@ -1291,7 +1291,7 @@ nvkm_vmm_pfn_map(struct nvkm_vmm *vmm, u8 shift, u64 addr, u64 size, u64 *pfn)
if (!page->shift || !IS_ALIGNED(addr, 1ULL << shift) ||
!IS_ALIGNED(size, 1ULL << shift) ||
- addr + size < addr || addr + size > vmm->limit) {
+ add_would_overflow(addr, size) || addr + size > vmm->limit) {
VMM_DEBUG(vmm, "paged map %d %d %016llx %016llx\n",
shift, page->shift, addr, size);
return -EINVAL;
--
2.34.1
prev parent reply other threads:[~2024-01-23 0:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20240122235208.work.748-kees@kernel.org>
2024-01-23 0:26 ` [PATCH 16/82] drm/nouveau/mmu: Refactor intentional wrap-around calculation Kees Cook
2024-01-23 0:27 ` Kees Cook [this message]
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