USB: usbmon: fix read(2)
There's a bug in the usbmon binary reader: When using read() to fetch the packets and a packet's data is partially read, the next read call will once again return up to len_cap bytes of data. The b_read counter is not regarded when determining the remaining chunk size. So, when dumping USB data with "cat /dev/usbmon0 > usbmon.trace" while reading from a USB storage device and analyzing the dump file afterwards it will get out of sync after a couple of packets. Signed-off-by: Ingo van Lil <inguin@gmx.de> Signed-off-by: Pete Zaitcev <zaitcev@redhat.com> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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@ -687,7 +687,10 @@ static ssize_t mon_bin_read(struct file *file, char __user *buf,
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}
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if (rp->b_read >= sizeof(struct mon_bin_hdr)) {
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step_len = min(nbytes, (size_t)ep->len_cap);
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step_len = ep->len_cap;
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step_len -= rp->b_read - sizeof(struct mon_bin_hdr);
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if (step_len > nbytes)
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step_len = nbytes;
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offset = rp->b_out + PKT_SIZE;
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offset += rp->b_read - sizeof(struct mon_bin_hdr);
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if (offset >= rp->b_size)
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