From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 26CF24A32; Wed, 30 Jul 2025 09:55:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753869310; cv=none; b=egQ+MKqQvVFdbLe+dUXMEbDJ6dp7vviWZ/jHRHN3lBDBPEQCFIG1sE55nJiZa+Zm52gCLXhxXaVBcPRFJVCjFqEHDx4tI6ImvswKZPFcfUz0psQ416WwLJ4jxLcIeVxlIKYayC+QJzUJ1ZVv6SaqJl4f/3bKZmrftRAOu00UjTU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753869310; c=relaxed/simple; bh=iQSANNrUC1ZAbxJ8YWw2ADD19XsGa5AoXo4nwAv8dsE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=ihSl+PT/B8U5RCyTZl2FcCybEg8VumDHbgMyTgmL0ehizHVGBH4Sy3+f1y9ybmDEOwG2184RuN59ysOMfwvOZ9Gd2glMhF8sBENe/NMR5W5Ic1+qpg6J0PlNQYtB2mnMENMAYE8pFzKrXDmFxA0zE74wMPbFlUt6e/CNlXpl/qU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=cl5ei353; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="cl5ei353" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79218C4CEF8; Wed, 30 Jul 2025 09:55:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1753869309; bh=iQSANNrUC1ZAbxJ8YWw2ADD19XsGa5AoXo4nwAv8dsE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cl5ei353XMoonpIRu+uidi0a5g7Ly2LbnnkM/zYLkL72c1hVs4ha4FADBxrfmQE1+ HMEcqPNfUXFIEL6tBbix464JqAouZrObIlt0EStbEagqOuu8TqExiZBYHViM+9F27g FjMkv+mg6q/ZB47wc8IpGLv8pWdAbY7Kx6J0YpeU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Thomas Zimmermann , Simona Vetter , =?UTF-8?q?Christian=20K=C3=B6nig?= , Zack Rusin , Sasha Levin Subject: [PATCH 6.15 86/92] Revert "drm/gem-shmem: Use dma_buf from GEM object instance" Date: Wed, 30 Jul 2025 11:36:34 +0200 Message-ID: <20250730093234.070807201@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250730093230.629234025@linuxfoundation.org> References: <20250730093230.629234025@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Zimmermann commit 6d496e9569983a0d7a05be6661126d0702cf94f7 upstream. This reverts commit 1a148af06000e545e714fe3210af3d77ff903c11. The dma_buf field in struct drm_gem_object is not stable over the object instance's lifetime. The field becomes NULL when user space releases the final GEM handle on the buffer object. This resulted in a NULL-pointer deref. Workarounds in commit 5307dce878d4 ("drm/gem: Acquire references on GEM handles for framebuffers") and commit f6bfc9afc751 ("drm/framebuffer: Acquire internal references on GEM handles") only solved the problem partially. They especially don't work for buffer objects without a DRM framebuffer associated. Hence, this revert to going back to using .import_attach->dmabuf. v3: - cc stable Signed-off-by: Thomas Zimmermann Reviewed-by: Simona Vetter Acked-by: Christian König Acked-by: Zack Rusin Cc: # v6.15+ Link: https://lore.kernel.org/r/20250715155934.150656-7-tzimmermann@suse.de Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_gem_shmem_helper.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -339,7 +339,7 @@ int drm_gem_shmem_vmap(struct drm_gem_sh int ret = 0; if (drm_gem_is_imported(obj)) { - ret = dma_buf_vmap(obj->dma_buf, map); + ret = dma_buf_vmap(obj->import_attach->dmabuf, map); } else { pgprot_t prot = PAGE_KERNEL; @@ -399,7 +399,7 @@ void drm_gem_shmem_vunmap(struct drm_gem struct drm_gem_object *obj = &shmem->base; if (drm_gem_is_imported(obj)) { - dma_buf_vunmap(obj->dma_buf, map); + dma_buf_vunmap(obj->import_attach->dmabuf, map); } else { dma_resv_assert_held(shmem->base.resv);