6.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Oliver Neukum <oneukum@xxxxxxxx>
commit e587a7633dfee8987a999cf253f7c52a8e09276c upstream.
printer_read() and printer_write() guard against the race
against disable() by checking the dev->interface flag,
which in turn is guarded by a spinlock.
These functions, however, drop the lock on multiple occasions.
This means that the test has to be redone after reacquiring
the lock and before doing IO.
Add the tests.
This also addresses CVE-2024-25741
Fixes: 7f2ca14d2f9b9 ("usb: gadget: function: printer: Interface is disabled and returns error")
Cc: stable <stable@xxxxxxxxxx>
Signed-off-by: Oliver Neukum <oneukum@xxxxxxxx>
Link: https://lore.kernel.org/r/20240620114039.5767-1-oneukum@xxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/gadget/function/f_printer.c | 39 +++++++++++++++++++++++---------
1 file changed, 29 insertions(+), 10 deletions(-)
--- a/drivers/usb/gadget/function/f_printer.c
+++ b/drivers/usb/gadget/function/f_printer.c
@@ -450,11 +450,8 @@ printer_read(struct file *fd, char __use
mutex_lock(&dev->lock_printer_io);
spin_lock_irqsave(&dev->lock, flags);
- if (dev->interface < 0) {
- spin_unlock_irqrestore(&dev->lock, flags);
- mutex_unlock(&dev->lock_printer_io);
- return -ENODEV;
- }
+ if (dev->interface < 0)
+ goto out_disabled;
/* We will use this flag later to check if a printer reset happened
* after we turn interrupts back on.
@@ -462,6 +459,9 @@ printer_read(struct file *fd, char __use
dev->reset_printer = 0;
setup_rx_reqs(dev);
+ /* this dropped the lock - need to retest */
+ if (dev->interface < 0)
+ goto out_disabled;
bytes_copied = 0;
current_rx_req = dev->current_rx_req;
@@ -495,6 +495,8 @@ printer_read(struct file *fd, char __use
wait_event_interruptible(dev->rx_wait,
(likely(!list_empty(&dev->rx_buffers))));
spin_lock_irqsave(&dev->lock, flags);
+ if (dev->interface < 0)
+ goto out_disabled;
}
/* We have data to return then copy it to the caller's buffer.*/
@@ -538,6 +540,9 @@ printer_read(struct file *fd, char __use
return -EAGAIN;
}
+ if (dev->interface < 0)
+ goto out_disabled;
+
/* If we not returning all the data left in this RX request
* buffer then adjust the amount of data left in the buffer.
* Othewise if we are done with this RX request buffer then
@@ -567,6 +572,11 @@ printer_read(struct file *fd, char __use
return bytes_copied;
else
return -EAGAIN;
+
+out_disabled:
+ spin_unlock_irqrestore(&dev->lock, flags);
+ mutex_unlock(&dev->lock_printer_io);
+ return -ENODEV;
}
static ssize_t
@@ -587,11 +597,8 @@ printer_write(struct file *fd, const cha
mutex_lock(&dev->lock_printer_io);
spin_lock_irqsave(&dev->lock, flags);
- if (dev->interface < 0) {
- spin_unlock_irqrestore(&dev->lock, flags);
- mutex_unlock(&dev->lock_printer_io);
- return -ENODEV;
- }
+ if (dev->interface < 0)
+ goto out_disabled;
/* Check if a printer reset happens while we have interrupts on */
dev->reset_printer = 0;
@@ -614,6 +621,8 @@ printer_write(struct file *fd, const cha
wait_event_interruptible(dev->tx_wait,
(likely(!list_empty(&dev->tx_reqs))));
spin_lock_irqsave(&dev->lock, flags);
+ if (dev->interface < 0)
+ goto out_disabled;
}
while (likely(!list_empty(&dev->tx_reqs)) && len) {
@@ -663,6 +672,9 @@ printer_write(struct file *fd, const cha
return -EAGAIN;
}
+ if (dev->interface < 0)
+ goto out_disabled;
+
list_add(&req->list, &dev->tx_reqs_active);
/* here, we unlock, and only unlock, to avoid deadlock. */
@@ -675,6 +687,8 @@ printer_write(struct file *fd, const cha
mutex_unlock(&dev->lock_printer_io);
return -EAGAIN;
}
+ if (dev->interface < 0)
+ goto out_disabled;
}
spin_unlock_irqrestore(&dev->lock, flags);
@@ -686,6 +700,11 @@ printer_write(struct file *fd, const cha
return bytes_copied;
else
return -EAGAIN;
+
+out_disabled:
+ spin_unlock_irqrestore(&dev->lock, flags);
+ mutex_unlock(&dev->lock_printer_io);
+ return -ENODEV;
}
static int
