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Mon, 09 Nov 2026 12:23:44 -0800 (PST) Received: from DESKTOP-6A237H8.localdomain ([106.219.176.229]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-1b3b5890584sm1520455c88.3.2026.11.09.12.23.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Nov 2026 12:23:44 -0800 (PST) From: kaii-k To: nat@pixelcluster.dev, arunpravin.paneerselvam@amd.com Cc: ckoenig@amd.com, thomas.hellstrom@linux.intel.com, matthew.auld@intel.com, matthew.brost@intel.com, dri-devel@lists.freedesktop.org, Harsh Parmar Subject: [PATCH 3/3] drm/ttm: check for NULL resource in ttm_bo_vm_fault_reserved() Date: Tue, 10 Nov 2026 01:53:30 +0530 Message-ID: <20261109202330.1816799-3-harshicon28@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261109202330.1816799-1-harshicon28@gmail.com> References: <20261109202330.1816799-1-harshicon28@gmail.com> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Mailman-Approved-At: Tue, 10 Nov 2026 08:33:28 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "dri-devel" X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 From: Harsh Parmar A buffer object can legitimately have no backing store: a driver may call ttm_bo_init_reserved() with zero placements, which leaves bo->resource NULL. It can also become NULL after the backing store has been released. ttm_bo_vm_fault_reserved() passes bo->resource to ttm_mem_io_reserve() and dereferences it, causing a NULL pointer dereference when a fault hits a buffer with no backing store. Return VM_FAULT_SIGBUS if the buffer has no backing store. Fixes: d3116756a710 ("drm/ttm: rename bo->mem and make it a pointer") Signed-off-by: Harsh Parmar --- drivers/gpu/drm/ttm/ttm_bo_vm.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c index 872bf44..69dd6bd 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c @@ -205,6 +205,9 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf, if (unlikely(ret != 0)) return ret; + if (unlikely(!bo->resource)) + return VM_FAULT_SIGBUS; + err = ttm_mem_io_reserve(bo->bdev, bo->resource); if (unlikely(err != 0)) return VM_FAULT_SIGBUS; -- 2.53.0