From b4b6a257b298ccf87192f1a282562a80a2e67b3d Mon Sep 17 00:00:00 2001 From: =?utf8?q?Thomas=20Hellstr=C3=B6m?= Date: Tue, 7 Mar 2023 15:46:15 +0100 Subject: [PATCH] drm/ttm: Fix a NULL pointer dereference MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit commit af93565a88095d5813af064dc6b05dbef1c11925 upstream. The LRU mechanism may look up a resource in the process of being removed from an object. The locking rules here are a bit unclear but it looks currently like res->bo assignment is protected by the LRU lock, whereas bo->resource is protected by the object lock, while *clearing* of bo->resource is also protected by the LRU lock. This means that if we check that bo->resource points to the LRU resource under the LRU lock we should be safe. So perform that check before deciding to swap out a bo. That avoids dereferencing a NULL bo->resource in ttm_bo_swapout(). Fixes: 27a06b1672d8 ("drm/ttm: move the LRU into resource handling v4") Cc: Christian König Cc: Daniel Vetter Cc: Christian Koenig Cc: Huang Rui Cc: Alex Deucher Cc: Felix Kuehling Cc: Philip Yang Cc: Qiang Yu Cc: Matthew Auld Cc: Nirmoy Das Cc: Tvrtko Ursulin Cc: "Thomas Hellström" Cc: Anshuman Gupta Cc: Arunpravin Paneer Selvam Cc: dri-devel@lists.freedesktop.org Cc: # v5.19+ Signed-off-by: Thomas Hellström Reviewed-by: Christian König Link: https://patchwork.freedesktop.org/patch/msgid/20230307144621.10748-2-thomas.hellstrom@linux.intel.com Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/ttm/ttm_device.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c index e7147e3046378..b84f74807ca13 100644 --- a/drivers/gpu/drm/ttm/ttm_device.c +++ b/drivers/gpu/drm/ttm/ttm_device.c @@ -158,7 +158,7 @@ int ttm_device_swapout(struct ttm_device *bdev, struct ttm_operation_ctx *ctx, struct ttm_buffer_object *bo = res->bo; uint32_t num_pages; - if (!bo) + if (!bo || bo->resource != res) continue; num_pages = PFN_UP(bo->base.size); -- 2.39.5