From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from cstnet.cn (smtp25.cstnet.cn [159.226.251.25]) (using TLSv1.2 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3F1651B3925; Sun, 28 Jun 2026 13:34:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=159.226.251.25 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782653667; cv=none; b=iKPCcNIOJrzO5U/m4a9kjPRuQrHOtSAihmhE7Ci6IkMKo/s9an6j+z59Ts8n1ZRVV/bZm+aHflnBRS0yuuYbq2odwwpxpp6I8HP4Cjzb1caA/C6H7oCdRH9j7dOQHiVAGw2nmgFCfHpz53wMDjt+7CUdvvvoJuDTlUdq/DCs2Go= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782653667; c=relaxed/simple; bh=/1sxTxMpQ9pxYEHRx3xsZIuUp5pujBdHDQT0OjqhLHM=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=Itn5RIMLmzPxLdD9AueUX+EiQxPAFqwM04JgwurpsSzKI9nJfW3N+dnDjoGUyRLVkM+nOJ+iGs90n/192hoIiGeWYc5KhjI/PbCaovpMKKwknpnu1fHng7/xciGd1zxsdZMSY8m5s7t5gRPsOS+e1l+q+PWWR2Uq8jFi8gW0XTc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn; spf=pass smtp.mailfrom=iscas.ac.cn; arc=none smtp.client-ip=159.226.251.25 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iscas.ac.cn Received: from localhost.localdomain (unknown [117.182.74.7]) by APP-05 (Coremail) with SMTP id zQCowADXYQXOIkFqHpPGFQ--.24670S2; Sun, 28 Jun 2026 21:34:07 +0800 (CST) From: WenTao Liang To: maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch Cc: kees@kernel.org, dmitry.baryshkov@oss.qualcomm.com, tomi.valkeinen@ideasonboard.com, mcanal@igalia.com, vulab@iscas.ac.cn, suraj.kandpal@intel.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Greg KH , stable@vger.kernel.org Subject: [PATCH v2] drm/display: fix MST branch device refcount leak on DPCD write failure Date: Sun, 28 Jun 2026 21:33:44 +0800 Message-Id: <20260628133344.46188-1-vulab@iscas.ac.cn> X-Mailer: git-send-email 2.39.5 (Apple Git-154) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:zQCowADXYQXOIkFqHpPGFQ--.24670S2 X-Coremail-Antispam: 1UD129KBjvJXoW7urWrXw43AFWkWFy5Zw4DXFb_yoW8GFy3pr W2kry2vr97AanFyr4UZF18WFWDGa9rAa4fCF4UWw43Ww1UAr10ga48KFyagF17ArWIkF1f twsrCFy8CF9Fk3DanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUU9014x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26r4j6ryUM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4j 6F4UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s 0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xII jxv20xvE14v26r106r15McIj6I8E87Iv67AKxVW8JVWxJwAm72CE4IkC6x0Yz7v_Jr0_Gr 1lF7xvr2IYc2Ij64vIr41lF7I21c0EjII2zVCS5cI20VAGYxC7M4IIrI8v6xkF7I0E8cxa n2IY04v7MxkF7I0En4kS14v26r1q6r43MxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4 AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE 17CEb7AF67AKxVWUtVW8ZwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMI IF0xvE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4l IxAIcVC2z280aVAFwI0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AKxVW8Jr0_Cr1UYxBIda VFxhVjvjDU0xZFpf9x0JUQZ2fUUUUU= X-CM-SenderInfo: pyxotu46lvutnvoduhdfq/1tbiBgcMA2pBHYgILgAAsW drm_dp_add_mst_branch_device initializes mstb with refcount 1, and drm_dp_mst_topology_get_mstb increments it to 2. When drm_dp_dpcd_write_byte fails, out_unlock performs only one drm_dp_mst_topology_put_mstb, leaving the other reference stored in mgr->mst_primary. Since MST was not successfully enabled, no disable path will clean it up. Suggested-by: Greg KH Fixes: 7a3cbf590e63 ("drm/mst: Some style improvements in drm_dp_mst_topology_mgr_set_mst()") Cc: stable@vger.kernel.org Signed-off-by: WenTao Liang --- Changes in v2: - Fix patch format based on reviewer feedback --- drivers/gpu/drm/display/drm_dp_mst_topology.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c index 8757972e8e24..db9441c80cd5 100644 --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c @@ -3679,8 +3679,10 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms DP_MST_EN | DP_UP_REQ_EN | DP_UPSTREAM_IS_SRC); - if (ret < 0) + if (ret < 0) { + mgr->mst_primary = NULL; goto out_unlock; + } /* Write reset payload */ drm_dp_dpcd_clear_payload(mgr->aux); -- 2.39.5 (Apple Git-154)