From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 8C7FF424D47; Mon, 3 Aug 2026 17:56:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785779808; cv=none; b=NOf5DmcOV/1POe5jLtzy+396A9zG3YgTzp9wEShmz2nVLoR+5s1otvuzp5orGFAnOD4C+Z/iksOt66ljYsQs4VQTf+EWfgjkujNoV6+HopOLdgZQJ+WHE+UBFbQ7kOYWG4z4/YH3wvDYmumdVR+9tfOQBWVKmBAg8BjCZF/TqvE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785779808; c=relaxed/simple; bh=m4vt64u6cJX0WIWdq88CwwkdVG49bKzDv3Dzuhu5MZY=; h=Mime-Version:Content-Type:Date:Message-Id:Subject:Cc:To:From: References:In-Reply-To; b=Q30dQD9MxZvFKgsJMRr3RDaWgDkh/tYZ7QuODqpIqdGYG9yASVRh/NUyLp7ySi4zVr92OMwUuTSxF3L2w0PHm1AmfMIhqAq16YZRdC8OdTfBEiN8BZEnrhN8et+C2kNN7yzxdSYadoQ8EfwTWLG/4krI1oT8nbhtGPI1xBO8WVU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YcbQOOmE; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="YcbQOOmE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 969BF1F00A3A; Mon, 3 Aug 2026 17:56:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785779806; bh=0W2dA/tdnG6mWPGo2zM7KT0maUNZ2/vxD3OQ7HNm5g0=; h=Date:Subject:Cc:To:From:References:In-Reply-To; b=YcbQOOmEtOpQVHtYFHt/jXOGqQoQngTf+ugzZGePRvRRrYA8DOQsPqvRNLDpi/lzj jz9tFTlvR/UE2Bjl9JKWwTDydTq5SZga+Z8qVRBFNzRWbyMDFN/6lN9uz88qfXbVOS CZ9aL15nY/gzM590dE+d3fVM7iWfbUw+tO6kZbshW0d4gkLxc8zfUlevC+RNiEJlPS YAwiWrvq7LvJxBq2aAkFhj8xHmhvk4Uf5oBvYHKFYYyytz1eC4TbTgCu52KgGasT4+ L2H5s32RncX9xZrb/U2tXm9WKdItOazlEDBoJG6F4SwVGCNbY1oV2KR+IFq/0Ovy+m yDPdFyPTb288w== Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Mon, 03 Aug 2026 19:56:39 +0200 Message-Id: Subject: Re: [PATCH v2 9/9] drm/debugfs: hold device reference for the lifetime of open files Cc: "Miguel Ojeda" , "Boqun Feng" , "Gary Guo" , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , "Benno Lossin" , "Andreas Hindborg" , "Alice Ryhl" , "Trevor Gross" , "Daniel Almeida" , "Tamir Duberstein" , "Alexandre Courbot" , =?utf-8?q?Onur_=C3=96zkan?= , "Greg Kroah-Hartman" , "Rafael J. Wysocki" , "Maarten Lankhorst" , "Maxime Ripard" , "Thomas Zimmermann" , "David Airlie" , "Simona Vetter" , "Alexander Viro" , "Christian Brauner" , "Jan Kara" , "Matthew Brost" , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , =?utf-8?q?Ma=C3=ADra_Canal?= , "Melissa Wen" , "Wambui Karuga" , "Eric Anholt" , "Ben Gamari" , , , To: "Alvin Sun" From: "Danilo Krummrich" References: <20260731-tyr-debugfs-v2-v2-0-aea19eccb996@linux.dev> <20260731-tyr-debugfs-v2-v2-9-aea19eccb996@linux.dev> In-Reply-To: <20260731-tyr-debugfs-v2-v2-9-aea19eccb996@linux.dev> On Thu Jul 30, 2026 at 7:05 PM CEST, Alvin Sun wrote: > Hold a device reference (via drm_dev_get/put) across the lifetime of open > debugfs files. Prevents use-after-free when a device is unregistered whil= e > a debugfs file remains open. Both drm_debugfs_open (legacy info_list) > and drm_debugfs_entry_open (drm_debugfs_add_file) paths are covered. > > Fixes: 1c9cacbea8805 ("drm/debugfs: create device-centered debugfs functi= ons") > Fixes: 28a62277e06f9 ("drm: Convert proc files to seq_file and introduce = debugfs") > > Signed-off-by: Alvin Sun > --- > drivers/gpu/drm/drm_debugfs.c | 42 +++++++++++++++++++++++++++++++++++++= +---- > 1 file changed, 38 insertions(+), 4 deletions(-) > > diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.= c > index 38cf6ce387cc8..5262a708f1602 100644 > --- a/drivers/gpu/drm/drm_debugfs.c > +++ b/drivers/gpu/drm/drm_debugfs.c > @@ -159,11 +159,28 @@ static const struct drm_debugfs_info drm_debugfs_li= st[] =3D { > static int drm_debugfs_open(struct inode *inode, struct file *file) > { > struct drm_info_node *node =3D inode->i_private; > + struct drm_device *dev =3D node->minor->dev; > + int ret; > =20 > if (!device_is_registered(node->minor->kdev)) > return -ENODEV; > =20 > - return single_open(file, node->info_ent->show, node); > + drm_dev_get(dev); > + > + ret =3D single_open(file, node->info_ent->show, node); > + if (ret) > + drm_dev_put(dev); > + > + return ret; > +} > + > +static int drm_debugfs_release(struct inode *inode, struct file *file) > +{ > + struct drm_info_node *node =3D > + ((struct seq_file *)file->private_data)->private; > + > + drm_dev_put(node->minor->dev); > + return single_release(inode, file); > } This isn't needed; in drm_dev_unregister() we call debugfs_remove_recursive= (), which already waits for all in-flight file operations. The DRM device itsel= f is guaranteed to be valid as long as it is registered.