forked from Minki/linux
staging: comedi: don't allow read() on async command set up for "write"
If a Comedi asynchronous command has been set up for data transfer in the "write" direction on the current "read" subdevice (for those subdevices that support both directions), don't allow the "read" file operation as that would mess with the data in the comedi data buffer that is read by the low-level comedi hardware driver. Signed-off-by: Ian Abbott <abbotti@mev.co.uk> Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -2210,6 +2210,10 @@ static ssize_t comedi_read(struct file *file, char __user *buf, size_t nbytes,
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retval = -EACCES;
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retval = -EACCES;
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goto out;
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goto out;
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}
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}
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if (async->cmd.flags & CMDF_WRITE) {
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retval = -EINVAL;
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goto out;
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}
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add_wait_queue(&async->wait_head, &wait);
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add_wait_queue(&async->wait_head, &wait);
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while (nbytes > 0 && !retval) {
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while (nbytes > 0 && !retval) {
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@ -2249,6 +2253,10 @@ static ssize_t comedi_read(struct file *file, char __user *buf, size_t nbytes,
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retval = -EACCES;
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retval = -EACCES;
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break;
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break;
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}
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}
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if (async->cmd.flags & CMDF_WRITE) {
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retval = -EINVAL;
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break;
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}
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continue;
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continue;
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}
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}
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m = copy_to_user(buf, async->prealloc_buf +
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m = copy_to_user(buf, async->prealloc_buf +
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