USB: core: Make do_proc_control() and do_proc_bulk() killable

The USBDEVFS_CONTROL and USBDEVFS_BULK ioctls invoke
usb_start_wait_urb(), which contains an uninterruptible wait with a
user-specified timeout value.  If timeout value is very large and the
device being accessed does not respond in a reasonable amount of time,
the kernel will complain about "Task X blocked for more than N
seconds", as found in testing by syzbot:

INFO: task syz-executor.0:8700 blocked for more than 143 seconds.
      Not tainted 5.14.0-rc7-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.0  state:D stack:23192 pid: 8700 ppid:  8455 flags:0x00004004
Call Trace:
 context_switch kernel/sched/core.c:4681 [inline]
 __schedule+0xc07/0x11f0 kernel/sched/core.c:5938
 schedule+0x14b/0x210 kernel/sched/core.c:6017
 schedule_timeout+0x98/0x2f0 kernel/time/timer.c:1857
 do_wait_for_common+0x2da/0x480 kernel/sched/completion.c:85
 __wait_for_common kernel/sched/completion.c:106 [inline]
 wait_for_common kernel/sched/completion.c:117 [inline]
 wait_for_completion_timeout+0x46/0x60 kernel/sched/completion.c:157
 usb_start_wait_urb+0x167/0x550 drivers/usb/core/message.c:63
 do_proc_bulk+0x978/0x1080 drivers/usb/core/devio.c:1236
 proc_bulk drivers/usb/core/devio.c:1273 [inline]
 usbdev_do_ioctl drivers/usb/core/devio.c:2547 [inline]
 usbdev_ioctl+0x3441/0x6b10 drivers/usb/core/devio.c:2713
...

To fix this problem, this patch replaces usbfs's calls to
usb_control_msg() and usb_bulk_msg() with special-purpose code that
does essentially the same thing (as recommended in the comment for
usb_start_wait_urb()), except that it always uses a killable wait and
it uses GFP_KERNEL rather than GFP_NOIO.

Reported-and-tested-by: syzbot+ada0f7d3d9fd2016d927@syzkaller.appspotmail.com
Suggested-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20210903175312.GA468440@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index 9618ba6..fa66e6e 100644 (file)
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -32,6 +32,7 @@
 #include <linux/usb.h>
 #include <linux/usbdevice_fs.h>
 #include <linux/usb/hcd.h>     /* for usbcore internals */
+#include <linux/usb/quirks.h>
 #include <linux/cdev.h>
 #include <linux/notifier.h>
 #include <linux/security.h>
@@ -1102,14 +1103,55 @@ static int usbdev_release(struct inode *inode, struct file *file)
        return 0;
 }
 
+static void usbfs_blocking_completion(struct urb *urb)
+{
+       complete((struct completion *) urb->context);
+}
+
+/*
+ * Much like usb_start_wait_urb, but returns status separately from
+ * actual_length and uses a killable wait.
+ */
+static int usbfs_start_wait_urb(struct urb *urb, int timeout,
+               unsigned int *actlen)
+{
+       DECLARE_COMPLETION_ONSTACK(ctx);
+       unsigned long expire;
+       int rc;
+
+       urb->context = &ctx;
+       urb->complete = usbfs_blocking_completion;
+       *actlen = 0;
+       rc = usb_submit_urb(urb, GFP_KERNEL);
+       if (unlikely(rc))
+               return rc;
+
+       expire = (timeout ? msecs_to_jiffies(timeout) : MAX_SCHEDULE_TIMEOUT);
+       rc = wait_for_completion_killable_timeout(&ctx, expire);
+       if (rc <= 0) {
+               usb_kill_urb(urb);
+               *actlen = urb->actual_length;
+               if (urb->status != -ENOENT)
+                       ;       /* Completed before it was killed */
+               else if (rc < 0)
+                       return -EINTR;
+               else
+                       return -ETIMEDOUT;
+       }
+       *actlen = urb->actual_length;
+       return urb->status;
+}
+
 static int do_proc_control(struct usb_dev_state *ps,
                struct usbdevfs_ctrltransfer *ctrl)
 {
        struct usb_device *dev = ps->dev;
        unsigned int tmo;
        unsigned char *tbuf;
-       unsigned wLength;
+       unsigned int wLength, actlen;
        int i, pipe, ret;
+       struct urb *urb = NULL;
+       struct usb_ctrlrequest *dr = NULL;
 
        ret = check_ctrlrecip(ps, ctrl->bRequestType, ctrl->bRequest,
                              ctrl->wIndex);
@@ -1122,51 +1164,63 @@ static int do_proc_control(struct usb_dev_state *ps,
                        sizeof(struct usb_ctrlrequest));
        if (ret)
                return ret;
+
+       ret = -ENOMEM;
        tbuf = (unsigned char *)__get_free_page(GFP_KERNEL);
-       if (!tbuf) {
-               ret = -ENOMEM;
+       if (!tbuf)
                goto done;
-       }
+       urb = usb_alloc_urb(0, GFP_NOIO);
+       if (!urb)
+               goto done;
+       dr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_NOIO);
+       if (!dr)
+               goto done;
+
+       dr->bRequestType = ctrl->bRequestType;
+       dr->bRequest = ctrl->bRequest;
+       dr->wValue = cpu_to_le16(ctrl->wValue);
+       dr->wIndex = cpu_to_le16(ctrl->wIndex);
+       dr->wLength = cpu_to_le16(ctrl->wLength);
+
        tmo = ctrl->timeout;
        snoop(&dev->dev, "control urb: bRequestType=%02x "
                "bRequest=%02x wValue=%04x "
                "wIndex=%04x wLength=%04x\n",
                ctrl->bRequestType, ctrl->bRequest, ctrl->wValue,
                ctrl->wIndex, ctrl->wLength);
-       if ((ctrl->bRequestType & USB_DIR_IN) && ctrl->wLength) {
+
+       if ((ctrl->bRequestType & USB_DIR_IN) && wLength) {
                pipe = usb_rcvctrlpipe(dev, 0);
-               snoop_urb(dev, NULL, pipe, ctrl->wLength, tmo, SUBMIT, NULL, 0);
+               usb_fill_control_urb(urb, dev, pipe, (unsigned char *) dr, tbuf,
+                               wLength, NULL, NULL);
+               snoop_urb(dev, NULL, pipe, wLength, tmo, SUBMIT, NULL, 0);
 
                usb_unlock_device(dev);
-               i = usb_control_msg(dev, pipe, ctrl->bRequest,
-                                   ctrl->bRequestType, ctrl->wValue, ctrl->wIndex,
-                                   tbuf, ctrl->wLength, tmo);
+               i = usbfs_start_wait_urb(urb, tmo, &actlen);
                usb_lock_device(dev);
-               snoop_urb(dev, NULL, pipe, max(i, 0), min(i, 0), COMPLETE,
-                         tbuf, max(i, 0));
-               if ((i > 0) && ctrl->wLength) {
-                       if (copy_to_user(ctrl->data, tbuf, i)) {
+               snoop_urb(dev, NULL, pipe, actlen, i, COMPLETE, tbuf, actlen);
+               if (!i && actlen) {
+                       if (copy_to_user(ctrl->data, tbuf, actlen)) {
                                ret = -EFAULT;
-                               goto done;
+                               goto recv_fault;
                        }
                }
        } else {
-               if (ctrl->wLength) {
-                       if (copy_from_user(tbuf, ctrl->data, ctrl->wLength)) {
+               if (wLength) {
+                       if (copy_from_user(tbuf, ctrl->data, wLength)) {
                                ret = -EFAULT;
                                goto done;
                        }
                }
                pipe = usb_sndctrlpipe(dev, 0);
-               snoop_urb(dev, NULL, pipe, ctrl->wLength, tmo, SUBMIT,
-                       tbuf, ctrl->wLength);
+               usb_fill_control_urb(urb, dev, pipe, (unsigned char *) dr, tbuf,
+                               wLength, NULL, NULL);
+               snoop_urb(dev, NULL, pipe, wLength, tmo, SUBMIT, tbuf, wLength);
 
                usb_unlock_device(dev);
-               i = usb_control_msg(dev, pipe, ctrl->bRequest,
-                                   ctrl->bRequestType, ctrl->wValue, ctrl->wIndex,
-                                   tbuf, ctrl->wLength, tmo);
+               i = usbfs_start_wait_urb(urb, tmo, &actlen);
                usb_lock_device(dev);
-               snoop_urb(dev, NULL, pipe, max(i, 0), min(i, 0), COMPLETE, NULL, 0);
+               snoop_urb(dev, NULL, pipe, actlen, i, COMPLETE, NULL, 0);
        }
        if (i < 0 && i != -EPIPE) {
                dev_printk(KERN_DEBUG, &dev->dev, "usbfs: USBDEVFS_CONTROL "
@@ -1174,8 +1228,15 @@ static int do_proc_control(struct usb_dev_state *ps,
                           current->comm, ctrl->bRequestType, ctrl->bRequest,
                           ctrl->wLength, i);
        }
-       ret = i;
+       ret = (i < 0 ? i : actlen);
+
+ recv_fault:
+       /* Linger a bit, prior to the next control message. */
+       if (dev->quirks & USB_QUIRK_DELAY_CTRL_MSG)
+               msleep(200);
  done:
+       kfree(dr);
+       usb_free_urb(urb);
        free_page((unsigned long) tbuf);
        usbfs_decrease_memory_usage(PAGE_SIZE + sizeof(struct urb) +
                        sizeof(struct usb_ctrlrequest));
@@ -1195,10 +1256,11 @@ static int do_proc_bulk(struct usb_dev_state *ps,
                struct usbdevfs_bulktransfer *bulk)
 {
        struct usb_device *dev = ps->dev;
-       unsigned int tmo, len1, pipe;
-       int len2;
+       unsigned int tmo, len1, len2, pipe;
        unsigned char *tbuf;
        int i, ret;
+       struct urb *urb = NULL;
+       struct usb_host_endpoint *ep;
 
        ret = findintfep(ps->dev, bulk->ep);
        if (ret < 0)
@@ -1206,14 +1268,17 @@ static int do_proc_bulk(struct usb_dev_state *ps,
        ret = checkintf(ps, ret);
        if (ret)
                return ret;
+
+       len1 = bulk->len;
+       if (len1 < 0 || len1 >= (INT_MAX - sizeof(struct urb)))
+               return -EINVAL;
+
        if (bulk->ep & USB_DIR_IN)
                pipe = usb_rcvbulkpipe(dev, bulk->ep & 0x7f);
        else
                pipe = usb_sndbulkpipe(dev, bulk->ep & 0x7f);
-       if (!usb_maxpacket(dev, pipe, !(bulk->ep & USB_DIR_IN)))
-               return -EINVAL;
-       len1 = bulk->len;
-       if (len1 >= (INT_MAX - sizeof(struct urb)))
+       ep = usb_pipe_endpoint(dev, pipe);
+       if (!ep || !usb_endpoint_maxp(&ep->desc))
                return -EINVAL;
        ret = usbfs_increase_memory_usage(len1 + sizeof(struct urb));
        if (ret)
@@ -1223,17 +1288,29 @@ static int do_proc_bulk(struct usb_dev_state *ps,
         * len1 can be almost arbitrarily large.  Don't WARN if it's
         * too big, just fail the request.
         */
+       ret = -ENOMEM;
        tbuf = kmalloc(len1, GFP_KERNEL | __GFP_NOWARN);
-       if (!tbuf) {
-               ret = -ENOMEM;
+       if (!tbuf)
+               goto done;
+       urb = usb_alloc_urb(0, GFP_KERNEL);
+       if (!urb)
                goto done;
+
+       if ((ep->desc.bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) ==
+                       USB_ENDPOINT_XFER_INT) {
+               pipe = (pipe & ~(3 << 30)) | (PIPE_INTERRUPT << 30);
+               usb_fill_int_urb(urb, dev, pipe, tbuf, len1,
+                               NULL, NULL, ep->desc.bInterval);
+       } else {
+               usb_fill_bulk_urb(urb, dev, pipe, tbuf, len1, NULL, NULL);
        }
+
        tmo = bulk->timeout;
        if (bulk->ep & 0x80) {
                snoop_urb(dev, NULL, pipe, len1, tmo, SUBMIT, NULL, 0);
 
                usb_unlock_device(dev);
-               i = usb_bulk_msg(dev, pipe, tbuf, len1, &len2, tmo);
+               i = usbfs_start_wait_urb(urb, tmo, &len2);
                usb_lock_device(dev);
                snoop_urb(dev, NULL, pipe, len2, i, COMPLETE, tbuf, len2);
 
@@ -1253,12 +1330,13 @@ static int do_proc_bulk(struct usb_dev_state *ps,
                snoop_urb(dev, NULL, pipe, len1, tmo, SUBMIT, tbuf, len1);
 
                usb_unlock_device(dev);
-               i = usb_bulk_msg(dev, pipe, tbuf, len1, &len2, tmo);
+               i = usbfs_start_wait_urb(urb, tmo, &len2);
                usb_lock_device(dev);
                snoop_urb(dev, NULL, pipe, len2, i, COMPLETE, NULL, 0);
        }
        ret = (i < 0 ? i : len2);
  done:
+       usb_free_urb(urb);
        kfree(tbuf);
        usbfs_decrease_memory_usage(len1 + sizeof(struct urb));
        return ret;