From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from stravinsky.debian.org (stravinsky.debian.org [82.195.75.108]) (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 180D34A341F for ; Tue, 5 May 2026 18:45:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=82.195.75.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778006721; cv=none; b=l4GwbkFctERACyh1q1spkKOzDK+qHYWvnF7fbBHcuBabVO7IkKOwvBuiZ4Rw/NHrlu28os8/zRWa3Aosri19XvmnR1Yn04atyW9XN/kQT0ITkpMOq64qBGl92EyKR3r75Aa4rTEtWfZvqedtcRf8yJAbo1yD6I3AfGCi7o78Ryc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778006721; c=relaxed/simple; bh=iV+FqaZYkVuau7UWTy+Lf/bB2fwRC9oLeAYPXQzrm6k=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=VEeMm4EFV65C1w/kJuqPfjv/BoLCbMvsqfR5g3VsLkK4lT4pAWKxY8lJmGTGMI2Nz9zyK1gds5xcZE9749ohBVegpAHPznIHTu33C58bECCb3q3TXwIG7ASbYE0rLMS6QkHObyADpb4uWsJLJuzv6GD7x6P3+D/HJgrHc2pEeD8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org; spf=pass smtp.mailfrom=debian.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b=i5f2hbyJ; arc=none smtp.client-ip=82.195.75.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=debian.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b="i5f2hbyJ" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:Content-Type:MIME-Version:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:In-Reply-To:References; bh=NkdjHjbL3u13LXUCbwCMIAA14HpmA0Llm99NgW5sonE=; b=i5f2hbyJlUWvKZhSy0KlG8tsGn 8ANEcNstJ9RlBgc5mbZjmaT3McHmLBVnI8Kmrr+Jq2LF7ypIug6N3juf614j7I/Oe/Fv+4i4HxgJY 3+IFGX0uWtyXY4LQfSG8GTqVc5fu5nguBaAduU5mP44yA3KBQ0VWycgPWXqHf+J+pGmQqlC46+Rwf PF7BEYm9LwriDRKIZDxrnCMou7aZs3zBeUKjAy0hO/2C+P5Uuwx1x4KwTPgCuvM/0eInnQk8tSiYl wulAN7Hceh1s2TijpjooJH+SFp4jIOWuByv3dlBMkvb/ndgo02MOs7mi7Beo92MktPQSXzGYVgxVD uK0TUgsA==; Received: from authenticated user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.96) (envelope-from ) id 1wKKld-0030ka-2H; Tue, 05 May 2026 18:45:14 +0000 Date: Tue, 5 May 2026 20:45:12 +0200 From: Ben Hutchings To: Sudip Mukherjee , Greg Kroah-Hartman Cc: 1130365@bugs.debian.org, Paul Menzel , stable@vger.kernel.org, linux-parport@lists.infradead.org Subject: [PATCH] parport: Fix race between port and client registration Message-ID: Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="oFaP8Rm7b43qwgz2" Content-Disposition: inline X-Debian-User: benh --oFaP8Rm7b43qwgz2 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable The parport subsystem registers port devices before they are fully initialised, resulting in a race condition where client drivers such as lp can attach to ports that are not completely initialised or even being torn down. When the port and client drivers are built as modules and loaded around the same time during boot, this occasionally results in a crash. I was able to make this happen reliably in a VM with a PC-style parallel port by patching parport_pc to fail probing: > --- a/drivers/parport/parport_pc.c > +++ b/drivers/parport/parport_pc.c > @@ -2069,7 +2069,7 @@ static struct parport *__parport_pc_probe_port(unsi= gned long int base, > if (!p) > goto out3; > > - base_res =3D request_region(base, 3, p->name); > + base_res =3D NULL; > if (!base_res) > goto out4; > and then running: while true; do modprobe lp & modprobe parport_pc wait rmmod lp parport_pc done for a few seconds. In the long term I think port registration should be changed to put the call to device_add() inside parport_announce_port(), but since the latter currently cannot fail this will require changing all port drivers. For now, add a flag to indicate whether a port has been "announced" and only try to attach client drivers to ports when the flag is set. Fixes: 6fa45a226897 ("parport: add device-model to parport subsystem") Closes: https://bugs.debian.org/1130365 Closes: https://lore.kernel.org/all/6ba903ad-9897-42bb-8c2d-337385cc3746@mo= lgen.mpg.de/ Cc: stable@vger.kernel.org Signed-off-by: Ben Hutchings --- drivers/parport/share.c | 11 +++++++++-- include/linux/parport.h | 1 + 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/parport/share.c b/drivers/parport/share.c index ba5292828703..eb0977ca1605 100644 --- a/drivers/parport/share.c +++ b/drivers/parport/share.c @@ -214,10 +214,14 @@ static void get_lowlevel_driver(void) static int port_check(struct device *dev, void *dev_drv) { struct parport_driver *drv =3D dev_drv; + struct parport *port; =20 /* only send ports, do not send other devices connected to bus */ - if (is_parport(dev)) - drv->match_port(to_parport_dev(dev)); + if (is_parport(dev)) { + port =3D to_parport_dev(dev); + if (test_bit(PARPORT_ANNOUNCED, &port->devflags)) + drv->match_port(port); + } return 0; } =20 @@ -532,6 +536,7 @@ void parport_announce_port(struct parport *port) if (slave) attach_driver_chain(slave); } + set_bit(PARPORT_ANNOUNCED, &port->devflags); mutex_unlock(®istration_lock); } EXPORT_SYMBOL(parport_announce_port); @@ -561,6 +566,8 @@ void parport_remove_port(struct parport *port) =20 mutex_lock(®istration_lock); =20 + clear_bit(PARPORT_ANNOUNCED, &port->devflags); + /* Spread the word. */ detach_driver_chain(port); =20 diff --git a/include/linux/parport.h b/include/linux/parport.h index 464c2ad28039..f64cb0676e3b 100644 --- a/include/linux/parport.h +++ b/include/linux/parport.h @@ -240,6 +240,7 @@ struct parport { =20 unsigned long devflags; #define PARPORT_DEVPROC_REGISTERED 0 +#define PARPORT_ANNOUNCED 1 struct pardevice *proc_device; /* Currently register proc device */ =20 struct list_head full_list; --oFaP8Rm7b43qwgz2 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEErCspvTSmr92z9o8157/I7JWGEQkFAmn6OrMACgkQ57/I7JWG EQniyg/8DI/t3+V54LsZso7KV7VFI2qO5/U9uutYBkJYOMhj5wpB+kR/71ohenmk EjhgWRpR3GIbJIN0s05byQ/OC4x8h32erkE1KUx0exOYu8KT908R1u0fBgHqCBvv FV7dEwI+K3UxGO5vXy/9A6XrunutzCDX4q0sFi4KmZQEYKDjnT4JPzxu2JGaBu8r /kKrBpbf2LeN82p+gD+gPrn2oYNxlCnQQcR00TiUQPI/JxjLWXPLqtWKF9tHjGRh aPCCqb8Is+lsnDciVrqZPJiZ/EU+bKOmZdyK2G1SNXkrljbmOFbHAisLLu3dKHe2 WuyCJxCosscX5S9+0bsrb93MASHJl6DuvD0aiqNXYe+BnKSHy7FvomqvG/ip+txQ 4rEc0chyTFchuNgtHNVPsury3fQPsKI6t+T36uk5GXscyuG5etwwKn+beFokRUgm WFwkhzRPyaSHBrAsu/0Uo63ROyMssVYpxd+cMpe+GS9f4jgZ2rbp2X8CHokJy5mV jMtiKzTUvAbkfKEog5U8qH/1SImtzJaGlIbfZwvKjyLnntlBGk8Keg70isj5wR2G Dy6xutqLb5GteAXzc1jCawn/DJnxFfexzF1aiU0i0nRWPf2j6LV5j5LL3lZVTL1k TQn1ZK96QyYb0pz0njlSEr84AyWUZcbg7mCMqi64/5rwcSf1Bts= =0DIu -----END PGP SIGNATURE----- --oFaP8Rm7b43qwgz2--