From: Zack Rusin Date: Tue, 5 May 2026 22:22:22 +0000 (-0400) Subject: drm/vmwgfx: fix guest_memory_dirty bitfield clobbered as size X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=83195b778f2d109a3a4f3ffaba4dce7e4cdb58aa;p=thirdparty%2Flinux.git drm/vmwgfx: fix guest_memory_dirty bitfield clobbered as size Two sites in vmwgfx_resource.c assign boolean literals to res->guest_memory_size, which is an unsigned long allocation-size field; the intended target is the adjacent res->guest_memory_dirty bitfield. After the assignments the field holds 0 or 1 instead of the resource's MOB allocation size: - vmw_resource_release() writes 0 (false), and - vmw_resource_unbind_list() writes 1 (true). Subsequent revalidation paths read guest_memory_size when computing the dirty page range (vmw_bo_dirty_transfer_to_res()) and the buffer allocation size (vmw_resource_buf_alloc()), producing zero-length walks or wrap-around ranges that read or write past the MOB bitmap. The dirty-tracking intent of the original code (mark the resource as dirtied since the last sync) is also lost, since guest_memory_dirty is never updated. Rename both assignments to guest_memory_dirty. Fixes: 668b206601c5 ("drm/vmwgfx: Stop using raw ttm_buffer_object's") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4.7 Signed-off-by: Zack Rusin Reviewed-by: Ian Forbes Link: https://patch.msgid.link/20260505222728.519626-2-zack.rusin@broadcom.com --- diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c index 388011696941..e3a187a2c7a1 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c @@ -136,7 +136,7 @@ static void vmw_resource_release(struct kref *kref) val_buf.num_shared = 0; res->func->unbind(res, false, &val_buf); } - res->guest_memory_size = false; + res->guest_memory_dirty = false; vmw_resource_mob_detach(res); if (res->dirty) res->func->dirty_free(res); @@ -773,7 +773,7 @@ void vmw_resource_unbind_list(struct vmw_bo *vbo) if (!WARN_ON_ONCE(!res->func->unbind)) (void) res->func->unbind(res, res->res_dirty, &val_buf); - res->guest_memory_size = true; + res->guest_memory_dirty = true; res->res_dirty = false; vmw_resource_mob_detach(res); }