From 211ecfaaef186ee5230a77d054cdec7fbfc6724a Mon Sep 17 00:00:00 2001 From: Brad Spengler Date: Wed, 7 Jan 2026 12:12:36 -0500 Subject: [PATCH] drm/vmwgfx: Fix invalid kref_put callback in vmw_bo_dirty_release The kref_put() call uses (void *)kvfree as the release callback, which is incorrect. kref_put() expects a function with signature void (*release)(struct kref *), but kvfree has signature void (*)(const void *). Calling through an incompatible function pointer is undefined behavior. The code only worked by accident because ref_count is the first member of vmw_bo_dirty, making the kref pointer equal to the struct pointer. Fix this by adding a proper release callback that uses container_of() to retrieve the containing structure before freeing. Fixes: c1962742ffff ("drm/vmwgfx: Use kref in vmw_bo_dirty") Signed-off-by: Brad Spengler Signed-off-by: Zack Rusin Cc: Ian Forbes Link: https://patch.msgid.link/20260107171236.3573118-1-zack.rusin@broadcom.com --- drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c b/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c index fd4e76486f2d..45561bc1c9ef 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c @@ -260,6 +260,13 @@ out_no_dirty: return ret; } +static void vmw_bo_dirty_free(struct kref *kref) +{ + struct vmw_bo_dirty *dirty = container_of(kref, struct vmw_bo_dirty, ref_count); + + kvfree(dirty); +} + /** * vmw_bo_dirty_release - Release a dirty-tracking user from a buffer object * @vbo: The buffer object @@ -274,7 +281,7 @@ void vmw_bo_dirty_release(struct vmw_bo *vbo) { struct vmw_bo_dirty *dirty = vbo->dirty; - if (dirty && kref_put(&dirty->ref_count, (void *)kvfree)) + if (dirty && kref_put(&dirty->ref_count, vmw_bo_dirty_free)) vbo->dirty = NULL; }