From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793829543; b=c2lxKFzbOz/nNDI1ObHoEUffccfK7ny6RYD+HmcMK3OUnIY+NufhQ7hXd83In2T9cYBJ Q4CjmgWl29XuvREaUwngJ2Ad33ULPY6Tu5Mes/ZOZ4lU3DEN68yW2aa+bhSL4khCc830G 8Zwaso+T+EQwGxGW50nLI0roJoZJnZky0wn39CKH9JMePPutg1PX7FHJQf3JCCJZq5C8h YyussobD3PFBCXv0sYVBmbsglqcSbyP3L+p90Dpg2oVWpDDt6s72uZEZcH31pFPSawHW0 +eU9c1rbswEqBq6IDmLwl/qf7zJId2lRD5hA4JSbndQGRAw5L0UJBC/7uIb9i5Do/rA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793829543; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=lhlOlHEK28LwQ7m91NdWCWuxJSoe1ZTM424POaKDywE=; b=bdh40goET95LVcnxqbAvi3EDZ4Amf0g475vh2VPqZZq0XoS8fpy+KjcfHHV2zoxGIbdG p6/R4v+DBUiNqjx8qJ32c0C8hwVRhTCZk4eNMK2osqE/G+9Y/pAL87h7REl9lPAUJXkmv SeOQkO3glhg21ngFvt20pPVaonxUeufLvv1o9dXKL+y8XZ2jNlz039uIAVPF9zpF8hXOH rR+HVPeYBp3VCaHCJENanxPb6IVc/WulRomJ4t2LZ5x2p9iUIatk8IjjBFUmPNxbsq5SV jP6SLDdd52F5Zd/Gnu5ic/YlavP3L9l7dnk8NMwlEn038tMIlXaPygc5+lvAnEBKDVw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=JSUcnkh3; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7AE286074FBD; Wed, 4 Nov 2026 21:59:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=JSUcnkh3 Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA4EF1F00A1A; Wed, 4 Nov 2026 21:59:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793829543; bh=lhlOlHEK28LwQ7m91NdWCWuxJSoe1ZTM424POaKDywE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=JSUcnkh3mGzWynCmdJ4lTuBq+e5ebOzB5yOi5DSksPkJWAhF+3R00TzyKOXi0sPJO wdzHVti+JrpzDVUcSMO41yMhnQ0yLd0AqlAX65FDKN8+rs891bVkW/jzP5yC2DipI6 jZLTY6JCUVA2YG7IiO0eQZmTfOSbrVDTsOLlBDWI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Pei Xiao , Sasha Levin Subject: [PATCH 6.18 0193/1005] ipack: ipoctal: add rwsem to guard against TOCTOU in remove path Date: Wed, 4 Nov 2026 15:58:46 -0500 Message-ID: <20261104211049.201357667@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211043.516122098@linuxfoundation.org> References: <20261104211043.516122098@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pei Xiao [ Upstream commit 7d3a708af7f4e2af9e114d731bd60d30c1ec884e ] The "removed" flag check in each tty op has a TOCTOU race with __ipoctal_remove(): the device could be removed between the flag check and the subsequent access to hardware resources (channel registers via iowrite8, or xmit_buf in write_tty). Close this race by introducing a read-write semaphore (remove_sem). The tty ops acquire the read lock via guard(rwsem_read) for the full duration of the operation, while __ipoctal_remove() acquires the write lock via scoped_guard(rwsem_write) when setting the removed flag. This ensures that once removed is true, no in-flight tty op can still be accessing resources that are about to be freed by the remove path. Signed-off-by: Pei Xiao Link: https://patch.msgid.link/fbce75010a0f0a3a3709a5e06fd0ffd19ca0a0ed.1782870760.git.xiaopei01@kylinos.cn Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/ipack/devices/ipoctal.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/drivers/ipack/devices/ipoctal.c b/drivers/ipack/devices/ipoctal.c index 474b58858dca6..aab303c4a9837 100644 --- a/drivers/ipack/devices/ipoctal.c +++ b/drivers/ipack/devices/ipoctal.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -54,6 +55,7 @@ struct ipoctal { u8 __iomem *int_space; struct kref kref; struct module *carrier_owner; + struct rw_semaphore remove_sem; bool removed; }; @@ -81,7 +83,7 @@ static int ipoctal_port_activate(struct tty_port *port, struct tty_struct *tty) channel = dev_get_drvdata(tty->dev); ipoctal = chan_to_ipoctal(channel, tty->index); - + guard(rwsem_read)(&ipoctal->remove_sem); if (ipoctal->removed) return -ENODEV; @@ -476,7 +478,7 @@ static ssize_t ipoctal_write_tty(struct tty_struct *tty, const u8 *buf, struct ipoctal *ipoctal = chan_to_ipoctal(channel, tty->index); size_t char_copied; - + guard(rwsem_read)(&ipoctal->remove_sem); if (ipoctal->removed || !channel->tty_port.xmit_buf) return 0; @@ -522,7 +524,7 @@ static void ipoctal_set_termios(struct tty_struct *tty, struct ipoctal *ipoctal = chan_to_ipoctal(channel, tty->index); speed_t baud; - + guard(rwsem_read)(&ipoctal->remove_sem); if (ipoctal->removed) return; @@ -660,7 +662,7 @@ static void ipoctal_hangup(struct tty_struct *tty) return; ipoctal = chan_to_ipoctal(channel, tty->index); - + guard(rwsem_read)(&ipoctal->remove_sem); if (ipoctal->removed) return; @@ -686,7 +688,7 @@ static void ipoctal_shutdown(struct tty_struct *tty) return; ipoctal = chan_to_ipoctal(channel, tty->index); - + guard(rwsem_read)(&ipoctal->remove_sem); if (ipoctal->removed) return; @@ -736,6 +738,7 @@ static int ipoctal_probe(struct ipack_device *dev) return -ENOMEM; kref_init(&ipoctal->kref); + init_rwsem(&ipoctal->remove_sem); ipoctal->dev = dev; ipoctal->carrier_owner = dev->bus->owner; @@ -755,7 +758,8 @@ static void __ipoctal_remove(struct ipoctal *ipoctal) { int i; - ipoctal->removed = true; + scoped_guard(rwsem_write, &ipoctal->remove_sem) + ipoctal->removed = true; ipoctal->dev->bus->ops->free_irq(ipoctal->dev); -- 2.53.0