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 30BD43C8732; Fri, 31 Jul 2026 08:24:07 +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=1785486253; cv=none; b=Wzh8TEChpKCjMRTS736SRg+MoStOA/vi3bos2AA0+JvLgF+PSd9zMug8W5Kw1yQeJSl5y/rFRYpUZnM3XP9Tuf1jYTBB/qanMZxRENyD27U+VgUWRDi4LB9T33uP0w8mgV3Z2jMv9x0TLgOjvJVkSrFpdhDKM5nrIchhkebi2SE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785486253; c=relaxed/simple; bh=uaT3RI9nmflxJ/7kpxRGyP5PQy9sTyvrAmRO6ZGaK/c=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=bZyKTjcpXHCAA0yzINCqb2nrud0Znbtby2+Lc5ZEWkhvASSZEKeVpCNHGZrMCNPhzewHFPuG+cZKYeMm+U6hs/c+xLNcgI1LlyCOsGyHXt9nh7qbB+ndlhneNagGRxb1SMcYsa1Gqb6xbK2MiGW1xcpLVqyml221r/DIpg9TTYg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PIXMKy60; 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="PIXMKy60" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 034D81F00A3A; Fri, 31 Jul 2026 08:24:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785486245; bh=1ESc4CQiJNiqVcMcL70lkVes9YgcpmoNar7aC6kk5vg=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=PIXMKy60rzCTasYVYIKP3FpEHK+Q/W1RWY5Ua0w3WheXGCZLCWL0Pc64a6eMvEIT/ XCB6/UUJMuvR/gXfaxa5dZ/g/UxHBUOQxpuj9vaFxV7h6TYCtQOZf4l7pPmrlgIfW6 FcSCxsD3vrYgyN5YXXMXyisLuih6jM4OsdlxatHvpv69zu8svYbcEn2MZfHETPaKc4 x83oltuAvkc5hl8mD3bnBcGJROskEyxcUHYtvn+2HBOgXntJO8Xvk98nIc48/EYs36 5ShcE7GtHH3s225VhW+QY3ddzReVmg9399XIRjG3si1Z6AJC1LE/xK2ub4jrFewDgN qpLJ4C4jsP4bw== Message-ID: Date: Fri, 31 Jul 2026 10:24:02 +0200 Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] serdev: use tty_port_tty_get() in ttyport_write_buf() to prevent UAF To: Greg Kroah-Hartman , Markus Probst , linux-serial@vger.kernel.org Cc: Rob Herring , linux-kernel@vger.kernel.org, Joshua Rogers , stable References: <20260731-aisle-tty-serdev-v1-0-2401a3189327@linuxfoundation.org> <20260731-aisle-tty-serdev-v1-2-2401a3189327@linuxfoundation.org> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 31. 07. 26, 10:06, Greg Kroah-Hartman wrote: > From: Joshua Rogers > > ttyport_write_buf() snapshots serport->tty as a raw pointer without > taking a reference, while ttyport_close() can concurrently release the > tty via tty_release_struct(), leading to a use-after-free. Use > tty_port_tty_get() to obtain a reference-counted tty pointer, matching > the pattern already used by ttyport_write_wakeup(). > > Assisted-by: AISLE:Snapshot > Cc: stable > Signed-off-by: Joshua Rogers > Signed-off-by: Greg Kroah-Hartman > --- > drivers/tty/serdev/serdev-ttyport.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/drivers/tty/serdev/serdev-ttyport.c b/drivers/tty/serdev/serdev-ttyport.c > index 48ce5b3f8308..4d37c8130dd7 100644 > --- a/drivers/tty/serdev/serdev-ttyport.c > +++ b/drivers/tty/serdev/serdev-ttyport.c > @@ -85,13 +85,21 @@ static const struct tty_port_client_operations client_ops = { > static ssize_t ttyport_write_buf(struct serdev_controller *ctrl, const u8 *data, size_t len) > { > struct serport *serport = serdev_controller_get_drvdata(ctrl); > - struct tty_struct *tty = serport->tty; > + struct tty_struct *tty; > + ssize_t ret; > > if (!test_bit(SERPORT_ACTIVE, &serport->flags)) > return 0; > > + tty = tty_port_tty_get(serport->port); > + if (!tty) > + return 0; > + > set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); > - return tty->ops->write(serport->tty, data, len); > + ret = tty->ops->write(tty, data, len); > + tty_kref_put(tty); Here, scope_guard(tty_port_tty, serport->port) { struct tty_struct *tty = scoped_tty(); set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); return tty->ops->write(serport->tty, data, len); } return 0; appears to be cleaner. thanks, -- js suse labs