linux-hardening - [PATCH] drm/amdgpu: Annotate struct amdgpu_bo_list with __counted

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Message-Id: <20231003232952.work.158-kees@kernel.org>
Date: Tue,  3 Oct 2023 16:29:52 -0700
From: Kees Cook <keescook@...omium.org>
To: Alex Deucher <alexander.deucher@....com>
Cc: Kees Cook <keescook@...omium.org>,
	Christian König <christian.koenig@....com>,
	"Pan, Xinhui" <Xinhui.Pan@....com>,
	David Airlie <airlied@...il.com>,
	Daniel Vetter <daniel@...ll.ch>,
	"Gustavo A. R. Silva" <gustavoars@...nel.org>,
	Luben Tuikov <luben.tuikov@....com>,
	Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	Felix Kuehling <Felix.Kuehling@....com>,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org,
	linux-hardening@...r.kernel.org,
	Nathan Chancellor <nathan@...nel.org>,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	Tom Rix <trix@...hat.com>,
	Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@....com>,
	linux-kernel@...r.kernel.org,
	llvm@...ts.linux.dev
Subject: [PATCH] drm/amdgpu: Annotate struct amdgpu_bo_list with __counted_by

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for
array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct amdgpu_bo_list.
Additionally, since the element count member must be set before accessing
the annotated flexible array member, move its initialization earlier.

Cc: Alex Deucher <alexander.deucher@....com>
Cc: "Christian König" <christian.koenig@....com>
Cc: "Pan, Xinhui" <Xinhui.Pan@....com>
Cc: David Airlie <airlied@...il.com>
Cc: Daniel Vetter <daniel@...ll.ch>
Cc: "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc: Luben Tuikov <luben.tuikov@....com>
Cc: Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc: Felix Kuehling <Felix.Kuehling@....com>
Cc: amd-gfx@...ts.freedesktop.org
Cc: dri-devel@...ts.freedesktop.org
Cc: linux-hardening@...r.kernel.org
Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci [1]
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c | 2 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
index 6f5b641b631e..781e5c5ce04d 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
@@ -84,6 +84,7 @@ int amdgpu_bo_list_create(struct amdgpu_device *adev, struct drm_file *filp,
 
 	kref_init(&list->refcount);
 
+	list->num_entries = num_entries;
 	array = list->entries;
 
 	for (i = 0; i < num_entries; ++i) {
@@ -129,7 +130,6 @@ int amdgpu_bo_list_create(struct amdgpu_device *adev, struct drm_file *filp,
 	}
 
 	list->first_userptr = first_userptr;
-	list->num_entries = num_entries;
 	sort(array, last_entry, sizeof(struct amdgpu_bo_list_entry),
 	     amdgpu_bo_list_entry_cmp, NULL);
 
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
index 6a703be45d04..555cd6d877c3 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
@@ -56,7 +56,7 @@ struct amdgpu_bo_list {
 	 */
 	struct mutex bo_list_mutex;
 
-	struct amdgpu_bo_list_entry entries[];
+	struct amdgpu_bo_list_entry entries[] __counted_by(num_entries);
 };
 
 int amdgpu_bo_list_get(struct amdgpu_fpriv *fpriv, int id,
-- 
2.34.1