From f1c0a2a3aff53698f4855968d576464041d49b39 Mon Sep 17 00:00:00 2001 From: Pete Zaitcev Date: Fri, 14 Nov 2008 09:47:41 -0700 Subject: 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 Signed-off-by: Pete Zaitcev Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/usb/mon/mon_bin.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'drivers/usb/mon') diff --git a/drivers/usb/mon/mon_bin.c b/drivers/usb/mon/mon_bin.c index c9de3f027aab..e06810aef2df 100644 --- a/drivers/usb/mon/mon_bin.c +++ b/drivers/usb/mon/mon_bin.c @@ -687,7 +687,10 @@ static ssize_t mon_bin_read(struct file *file, char __user *buf, } if (rp->b_read >= sizeof(struct mon_bin_hdr)) { - step_len = min(nbytes, (size_t)ep->len_cap); + step_len = ep->len_cap; + step_len -= rp->b_read - sizeof(struct mon_bin_hdr); + if (step_len > nbytes) + step_len = nbytes; offset = rp->b_out + PKT_SIZE; offset += rp->b_read - sizeof(struct mon_bin_hdr); if (offset >= rp->b_size) -- cgit v1.2.1