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Message-ID: <ea4028b7-53f2-aeaf-76e7-69874efcdec5@I-love.SAKURA.ne.jp>
Date: Thu, 28 Jan 2021 15:09:14 +0900
From: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To: Shuah Khan <skhan@...uxfoundation.org>,
Hillf Danton <hdanton@...a.com>,
syzbot <syzbot+95ce4b142579611ef0a9@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org,
linux-security-module@...r.kernel.org,
Andrey Konovalov <andreyknvl@...gle.com>,
Valentina Manea <valentina.manea.m@...il.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
syzkaller-bugs@...glegroups.com
Subject: Re: general protection fault in tomoyo_socket_sendmsg_permission
On 2020/11/14 2:14, Shuah Khan wrote:
> On 11/13/20 5:00 AM, Hillf Danton wrote:
>> Thu, 12 Nov 2020 23:21:26 -0800
>>> syzbot found the following issue on:
>>>
>>> HEAD commit: 9dbc1c03 Merge tag 'xfs-5.10-fixes-3' of git://git.kernel...
>>> git tree: upstream
>>> console output: https://syzkaller.appspot.com/x/log.txt?x=10453034500000
>>> kernel config: https://syzkaller.appspot.com/x/.config?x=1735b7978b1c3721
>>> dashboard link: https://syzkaller.appspot.com/bug?extid=95ce4b142579611ef0a9
>>> compiler: gcc (GCC) 10.1.0-syz 20200507
>>> userspace arch: i386
>>>
>>> Unfortunately, I don't have any reproducer for this issue yet.
>>>
>
> I would like to see the reproducer for this. I just can't reproduce
> this problem.
>
>>
>> Fix 96c2737716d5 ("usbip: move usbip kernel code out of staging")
>> by closing the race between readers and writer of ud->tcp_socket on
>> sock shutdown. To do that, add waitqueue for usbip device and make
>> writer wait for all readers to go home before releasing the socket.
Worrysome part for me is vhci_device_reset() which resets ud->tcp_socket to NULL
without waiting for tx thread to terminate, though I don't know if
vhci_device_reset() can be called while tx thread is running.
I'd like to try below debug printk() patch on linx-next tree, for this bug is
reported on linux.git and linux-next.git trees. Which git tree can be used for
sending this to-be-removed patch to linux-next.git ? I wish there is a kernel
config for fuzzers in linux.git so that every git tree can carry debug printk()
patch for syzbot's reports...
Subject: [PATCH] usb: usbip: vhci_hcd: add printk() for debug
This is linux-next only patch for examining a bug reported at
https://syzkaller.appspot.com/bug?id=3e1d941a31361efc4ced2ba8b4af2044d4e43c59 .
Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
---
drivers/usb/usbip/stub_dev.c | 6 ++++++
drivers/usb/usbip/vhci_hcd.c | 11 +++++++++++
drivers/usb/usbip/vhci_sysfs.c | 4 ++++
drivers/usb/usbip/vhci_tx.c | 12 ++++++++++++
drivers/usb/usbip/vudc_dev.c | 6 ++++++
5 files changed, 39 insertions(+)
diff --git a/drivers/usb/usbip/stub_dev.c b/drivers/usb/usbip/stub_dev.c
index 2305d425e6c9..627f83c0ebc8 100644
--- a/drivers/usb/usbip/stub_dev.c
+++ b/drivers/usb/usbip/stub_dev.c
@@ -131,10 +131,14 @@ static void stub_shutdown_connection(struct usbip_device *ud)
/* 1. stop threads */
if (ud->tcp_rx) {
+ if (IS_BUILTIN(CONFIG_DEBUG_AID_FOR_SYZBOT))
+ pr_info("%s: stop rx %p\n", __func__, ud->tcp_rx);
kthread_stop_put(ud->tcp_rx);
ud->tcp_rx = NULL;
}
if (ud->tcp_tx) {
+ if (IS_BUILTIN(CONFIG_DEBUG_AID_FOR_SYZBOT))
+ pr_info("%s: stop tx %p\n", __func__, ud->tcp_tx);
kthread_stop_put(ud->tcp_tx);
ud->tcp_tx = NULL;
}
@@ -146,6 +150,8 @@ static void stub_shutdown_connection(struct usbip_device *ud)
* not touch NULL socket.
*/
if (ud->tcp_socket) {
+ if (IS_BUILTIN(CONFIG_DEBUG_AID_FOR_SYZBOT))
+ pr_info("%s: close sock %p\n", __func__, ud->tcp_socket);
sockfd_put(ud->tcp_socket);
ud->tcp_socket = NULL;
ud->sockfd = -1;
diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c
index 3209b5ddd30c..9e95bf9330f5 100644
--- a/drivers/usb/usbip/vhci_hcd.c
+++ b/drivers/usb/usbip/vhci_hcd.c
@@ -1016,10 +1016,14 @@ static void vhci_shutdown_connection(struct usbip_device *ud)
/* kill threads related to this sdev */
if (vdev->ud.tcp_rx) {
+ if (IS_BUILTIN(CONFIG_DEBUG_AID_FOR_SYZBOT))
+ pr_info("%s: stop rx %p\n", __func__, vdev->ud.tcp_rx);
kthread_stop_put(vdev->ud.tcp_rx);
vdev->ud.tcp_rx = NULL;
}
if (vdev->ud.tcp_tx) {
+ if (IS_BUILTIN(CONFIG_DEBUG_AID_FOR_SYZBOT))
+ pr_info("%s: stop tx %p\n", __func__, vdev->ud.tcp_tx);
kthread_stop_put(vdev->ud.tcp_tx);
vdev->ud.tcp_tx = NULL;
}
@@ -1027,6 +1031,8 @@ static void vhci_shutdown_connection(struct usbip_device *ud)
/* active connection is closed */
if (vdev->ud.tcp_socket) {
+ if (IS_BUILTIN(CONFIG_DEBUG_AID_FOR_SYZBOT))
+ pr_info("%s: close sock %p\n", __func__, ud->tcp_socket);
sockfd_put(vdev->ud.tcp_socket);
vdev->ud.tcp_socket = NULL;
vdev->ud.sockfd = -1;
@@ -1074,6 +1080,11 @@ static void vhci_device_reset(struct usbip_device *ud)
vdev->udev = NULL;
if (ud->tcp_socket) {
+ if (IS_BUILTIN(CONFIG_DEBUG_AID_FOR_SYZBOT)) {
+ pr_info("%s: close sock %p\n", __func__, ud->tcp_socket);
+ BUG_ON(vdev->ud.tcp_tx);
+ BUG_ON(vdev->ud.tcp_rx);
+ }
sockfd_put(ud->tcp_socket);
ud->tcp_socket = NULL;
ud->sockfd = -1;
diff --git a/drivers/usb/usbip/vhci_sysfs.c b/drivers/usb/usbip/vhci_sysfs.c
index be37aec250c2..b37e7770aa35 100644
--- a/drivers/usb/usbip/vhci_sysfs.c
+++ b/drivers/usb/usbip/vhci_sysfs.c
@@ -390,6 +390,10 @@ static ssize_t attach_store(struct device *dev, struct device_attribute *attr,
vdev->ud.tcp_rx = kthread_get_run(vhci_rx_loop, &vdev->ud, "vhci_rx");
vdev->ud.tcp_tx = kthread_get_run(vhci_tx_loop, &vdev->ud, "vhci_tx");
+ if (IS_BUILTIN(CONFIG_DEBUG_AID_FOR_SYZBOT)) {
+ BUG_ON(IS_ERR(vdev->ud.tcp_rx));
+ BUG_ON(IS_ERR(vdev->ud.tcp_tx));
+ }
rh_port_connect(vdev, speed);
diff --git a/drivers/usb/usbip/vhci_tx.c b/drivers/usb/usbip/vhci_tx.c
index 0ae40a13a9fe..05da652e7bbe 100644
--- a/drivers/usb/usbip/vhci_tx.c
+++ b/drivers/usb/usbip/vhci_tx.c
@@ -63,6 +63,9 @@ static int vhci_send_cmd_submit(struct vhci_device *vdev)
int iovnum;
int err = -ENOMEM;
int i;
+#ifdef CONFIG_DEBUG_AID_FOR_SYZBOT
+ struct socket *socket = vdev->ud.tcp_socket;
+#endif
while ((priv = dequeue_from_priv_tx(vdev)) != NULL) {
int ret;
@@ -135,6 +138,11 @@ static int vhci_send_cmd_submit(struct vhci_device *vdev)
iovnum++;
txsize += len;
}
+#ifdef CONFIG_DEBUG_AID_FOR_SYZBOT
+ if (!socket || socket != vdev->ud.tcp_socket)
+ pr_err("%s: sock changed from %p to %p\n",
+ __func__, socket, vdev->ud.tcp_socket);
+#endif
ret = kernel_sendmsg(vdev->ud.tcp_socket, &msg, iov, iovnum,
txsize);
@@ -237,6 +245,8 @@ int vhci_tx_loop(void *data)
struct usbip_device *ud = data;
struct vhci_device *vdev = container_of(ud, struct vhci_device, ud);
+ if (IS_BUILTIN(CONFIG_DEBUG_AID_FOR_SYZBOT))
+ pr_info("%s: thread starting %p\n", __func__, vdev->ud.tcp_tx);
while (!kthread_should_stop()) {
if (vhci_send_cmd_submit(vdev) < 0)
break;
@@ -251,6 +261,8 @@ int vhci_tx_loop(void *data)
usbip_dbg_vhci_tx("pending urbs ?, now wake up\n");
}
+ if (IS_BUILTIN(CONFIG_DEBUG_AID_FOR_SYZBOT))
+ pr_info("%s: thread exiting %p\n", __func__, vdev->ud.tcp_tx);
return 0;
}
diff --git a/drivers/usb/usbip/vudc_dev.c b/drivers/usb/usbip/vudc_dev.c
index c8eeabdd9b56..816cb4b5700b 100644
--- a/drivers/usb/usbip/vudc_dev.c
+++ b/drivers/usb/usbip/vudc_dev.c
@@ -437,15 +437,21 @@ static void vudc_shutdown(struct usbip_device *ud)
kernel_sock_shutdown(ud->tcp_socket, SHUT_RDWR);
if (ud->tcp_rx) {
+ if (IS_BUILTIN(CONFIG_DEBUG_AID_FOR_SYZBOT))
+ pr_info("%s: stop rx %p\n", __func__, ud->tcp_rx);
kthread_stop_put(ud->tcp_rx);
ud->tcp_rx = NULL;
}
if (ud->tcp_tx) {
+ if (IS_BUILTIN(CONFIG_DEBUG_AID_FOR_SYZBOT))
+ pr_info("%s: stop tx %p\n", __func__, ud->tcp_tx);
kthread_stop_put(ud->tcp_tx);
ud->tcp_tx = NULL;
}
if (ud->tcp_socket) {
+ if (IS_BUILTIN(CONFIG_DEBUG_AID_FOR_SYZBOT))
+ pr_info("%s: close sock %p\n", __func__, ud->tcp_socket);
sockfd_put(ud->tcp_socket);
ud->tcp_socket = NULL;
}
--
2.18.4
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