USB: cdc-acm: fix write and resume race
Fix race between write() and resume() due to improper locking that could
lead to writes being reordered.
Resume must be done atomically and susp_count be protected by the
write_lock in order to prevent racing with write(). This could otherwise
lead to writes being reordered if write() grabs the write_lock after
susp_count is decremented, but before the delayed urb is submitted.
Fixes: 11ea859d64
("USB: additional power savings for cdc-acm devices
that support remote wakeup")
Cc: <stable@vger.kernel.org> # v2.6.27
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Родитель
5a345c20c1
Коммит
e144ed28be
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@ -1541,27 +1541,20 @@ static int acm_resume(struct usb_interface *intf)
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struct acm *acm = usb_get_intfdata(intf);
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struct acm_wb *wb;
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int rv = 0;
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int cnt;
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spin_lock_irq(&acm->read_lock);
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acm->susp_count -= 1;
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cnt = acm->susp_count;
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spin_unlock_irq(&acm->read_lock);
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spin_lock(&acm->write_lock);
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if (cnt)
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return 0;
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if (--acm->susp_count)
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goto out;
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if (test_bit(ASYNCB_INITIALIZED, &acm->port.flags)) {
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rv = usb_submit_urb(acm->ctrlurb, GFP_NOIO);
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rv = usb_submit_urb(acm->ctrlurb, GFP_ATOMIC);
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spin_lock_irq(&acm->write_lock);
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if (acm->delayed_wb) {
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wb = acm->delayed_wb;
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acm->delayed_wb = NULL;
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spin_unlock_irq(&acm->write_lock);
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acm_start_wb(acm, wb);
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} else {
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spin_unlock_irq(&acm->write_lock);
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}
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/*
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@ -1569,12 +1562,14 @@ static int acm_resume(struct usb_interface *intf)
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* do the write path at all cost
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*/
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if (rv < 0)
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goto err_out;
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goto out;
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rv = acm_submit_read_urbs(acm, GFP_NOIO);
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rv = acm_submit_read_urbs(acm, GFP_ATOMIC);
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}
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out:
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spin_unlock(&acm->write_lock);
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spin_unlock_irq(&acm->read_lock);
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err_out:
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return rv;
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}
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