From patchwork Wed Aug 18 13:02:31 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wentao_Liang X-Patchwork-Id: 76439 Received: from vger.kernel.org ([23.128.96.18]) by www.linuxtv.org with esmtp (Exim 4.92) (envelope-from ) id 1mGLUM-004OKl-EG; Wed, 18 Aug 2021 13:20:14 +0000 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236473AbhHRNUp (ORCPT + 1 other); Wed, 18 Aug 2021 09:20:45 -0400 Received: from mail-m971.mail.163.com ([123.126.97.1]:43348 "EHLO mail-m971.mail.163.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235943AbhHRNUo (ORCPT ); Wed, 18 Aug 2021 09:20:44 -0400 X-Greylist: delayed 921 seconds by postgrey-1.27 at vger.kernel.org; Wed, 18 Aug 2021 09:20:43 EDT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Subject:Date:Message-Id:MIME-Version; bh=1ty22 VOMwZz6zNP9VFFtEN/bLi/9Opdu0wufpsZYxvU=; b=i7B4+rwLQ+mjFUw+4LiCg wuTOwj4+GIIggPwv/s+CqaBR5YrmzueXWvpchOZeltR7OomoWEgxjXu46GIz/Nga ukQC0qXZ0dOA3Quo59Pt0Ywa3h5QiIWMzHlplguIbLNAWJjdyLv6sP2XreKZZuzD EwMhX7wwXVHfiayv6MqLZk= Received: from localhost.localdomain (unknown [111.201.47.26]) by smtp1 (Coremail) with SMTP id GdxpCgD3FkzqBB1hdtlmOA--.179S4; Wed, 18 Aug 2021 21:02:41 +0800 (CST) From: Wentao_Liang To: maarten.lankhorst@linux.intel.com Cc: mripard@kernel.org, tzimmermann@suse.de, airlied@linux.ie, daniel@ffwll.ch, sumit.semwal@linaro.org, christian.koenig@amd.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, Wentao_Liang Subject: [PATCH] drm/prime: fix a potential double put (release) bug Date: Wed, 18 Aug 2021 21:02:31 +0800 Message-Id: <20210818130231.3484-1-Wentao_Liang_g@163.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-CM-TRANSID: GdxpCgD3FkzqBB1hdtlmOA--.179S4 X-Coremail-Antispam: 1Uf129KBjvJXoW7Kw4rGF4xWr43CrWDJr17Awb_yoW8Kr1fpF WYyFyUKrWUtF4jqFyfAF1kZan09w45Ga1xXrW3Jw4Yv3WFqr1DWF9rAr9Fyr15G34Dtw1S yFyUXry5JryUCF7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07jkYFAUUUUU= X-Originating-IP: [111.201.47.26] X-CM-SenderInfo: xzhq3t5rboxtpqjbwqqrwthudrp/xtbBQhHyL1++M90j-wAAsd Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-LSpam-Score: -3.2 (---) X-LSpam-Report: No, score=-3.2 required=5.0 tests=BAYES_00=-1.9,DKIM_SIGNED=0.1,DKIM_VALID=-0.1,DKIM_VALID_AU=-0.1,FREEMAIL_FORGED_FROMDOMAIN=0.001,FREEMAIL_FROM=0.001,HEADER_FROM_DIFFERENT_DOMAINS=0.5,MAILING_LIST_MULTI=-1,RCVD_IN_DNSWL_LOW=-0.7 autolearn=ham autolearn_force=no In line 317 (#1), drm_gem_prime_import() is called, it will call drm_gem_prime_import_dev(). At the end of the function drm_gem_prime_import_dev() (line 956, #2), "dma_buf_put(dma_buf);" puts dma_buf->file and may cause it to be released. However, after drm_gem_prime_import() returning, the dma_buf may be put again by the same put function in lines 342, 351 and 358 (#3, #4, #5). Putting the dma_buf improperly more than once can lead to an incorrect dma_buf- >file put. We believe that the put of the dma_buf in the function drm_gem_prime_import() is unnecessary (#2). We can fix the above bug by removing the redundant "dma_buf_put(dma_buf);" in line 956. 314 if (dev->driver->gem_prime_import) 315 obj = dev->driver->gem_prime_import(dev, dma_buf); 316 else 317 obj = drm_gem_prime_import(dev, dma_buf); //#1 call to drm_gem_prime_import // ->drm_gem_prime_import_dev // ->dma_buf_put ... 336 ret = drm_prime_add_buf_handle(&file_priv->prime, 337 dma_buf, *handle); ... 342 dma_buf_put(dma_buf); //#3 put again 343 344 return 0; 345 346 fail: 351 dma_buf_put(dma_buf); //#4 put again 352 return ret; 356 out_put: 357 mutex_unlock(&file_priv->prime.lock); 358 dma_buf_put(dma_buf); //#5 put again 359 return ret; 360 } 905 struct drm_gem_object *drm_gem_prime_import_dev (struct drm_device *dev, 906 struct dma_buf *dma_buf, 907 struct device *attach_dev) 908 { ... 952 fail_unmap: 953 dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL); 954 fail_detach: 955 dma_buf_detach(dma_buf, attach); 956 dma_buf_put(dma_buf); //#2 the first put of dma_buf // (unnecessary) 957 958 return ERR_PTR(ret); 959 } Signed-off-by: Wentao_Liang --- drivers/gpu/drm/drm_prime.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c index 2a54f86856af..cef03ad0d5cd 100644 --- a/drivers/gpu/drm/drm_prime.c +++ b/drivers/gpu/drm/drm_prime.c @@ -953,7 +953,6 @@ struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev, dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL); fail_detach: dma_buf_detach(dma_buf, attach); - dma_buf_put(dma_buf); return ERR_PTR(ret); }