From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pan Bian Subject: [PATCH] drm/i915/gvt: fix dropping obj reference twice Date: Wed, 6 Nov 2019 15:31:07 +0800 Message-ID: <1573025467-18278-1-git-send-email-bianpan2016@163.com> Return-path: Sender: linux-kernel-owner@vger.kernel.org To: Zhenyu Wang , Zhi Wang , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , David Airlie , Daniel Vetter Cc: intel-gvt-dev@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Pan Bian List-Id: intel-gfx@lists.freedesktop.org The reference count of obj will be decremented twice if error occurs in dma_buf_fd(). Additionally, attempting to read the reference count of obj after dropping reference may lead to a use after free bug. Here, we drop obj's reference until it is not used. Signed-off-by: Pan Bian --- drivers/gpu/drm/i915/gvt/dmabuf.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/gvt/dmabuf.c b/drivers/gpu/drm/i915/gvt/dmabuf.c index 13044c027f27..4bfaefdf548d 100644 --- a/drivers/gpu/drm/i915/gvt/dmabuf.c +++ b/drivers/gpu/drm/i915/gvt/dmabuf.c @@ -498,8 +498,6 @@ int intel_vgpu_get_dmabuf(struct intel_vgpu *vgpu, unsigned int dmabuf_id) goto out_free_gem; } - i915_gem_object_put(obj); - ret = dma_buf_fd(dmabuf, DRM_CLOEXEC | DRM_RDWR); if (ret < 0) { gvt_vgpu_err("create dma-buf fd failed ret:%d\n", ret); @@ -524,6 +522,8 @@ int intel_vgpu_get_dmabuf(struct intel_vgpu *vgpu, unsigned int dmabuf_id) file_count(dmabuf->file), kref_read(&obj->base.refcount)); + i915_gem_object_put(obj); + return dmabuf_fd; out_free_dmabuf: -- 2.7.4 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.5 required=3.0 tests=FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C158AC5DF63 for ; 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Wed, 06 Nov 2019 15:31:26 +0800 (CST) From: Pan Bian To: Zhenyu Wang , Zhi Wang , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , David Airlie , Daniel Vetter Date: Wed, 6 Nov 2019 15:31:07 +0800 Message-Id: <1573025467-18278-1-git-send-email-bianpan2016@163.com> X-Mailer: git-send-email 2.7.4 X-CM-TRANSID: HNxpCgCXRjG8dsJd0yl7BQ--.263S3 X-Coremail-Antispam: 1Uf129KBjvdXoWrtrW3tr1DXFWxKrWfKw1kGrg_yoWkurbEkr WYqF17CrZrKFs09r1jyr9rAas2gF4UZFW8W3y7t34kA342kw1DZFZ5Zr15Zr18uF4UAFZx AF1xury3ZFWF9jkaLaAFLSUrUUUUUb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUvcSsGvfC2KfnxnUUI43ZEXa7IU1xwIPUUUUU== X-Originating-IP: [202.112.113.212] X-CM-SenderInfo: held01tdqsiiqw6rljoofrz/xtbBUQ5lclaD5JcnsgAAs7 X-Mailman-Approved-At: Wed, 06 Nov 2019 17:34:22 +0000 X-Mailman-Original-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Subject:Date:Message-Id; bh=10j9yC2LKZ4Yu8yJAT 38Az579fi88WXpZdGmSsenJPQ=; b=UeYFaws6OMq6xy765lPDJs+n7oC6z4TtQl vbRk9uEz0iZ5qE5YN/NlX6LAaS6zPv86MgtPDw1tUc0aA3+UGA6XpunNBUnojJrF 09FfMGQxsNFdoFNXRD1fYqiB3jW7aUpe7OYDqcjV3jUpHLrIU5rbsXXXcJ/Aeqzm R+rHk2M8c= Subject: [Intel-gfx] [PATCH] drm/i915/gvt: fix dropping obj reference twice X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Pan Bian , intel-gfx@lists.freedesktop.org, intel-gvt-dev@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org MIME-Version: 1.0 Content-Type: text/plain; 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