diff options
authorPete Zaitcev <>2008-11-14 09:47:41 -0700
committerGreg Kroah-Hartman <>2008-11-19 22:01:35 -0800
commitf1c0a2a3aff53698f4855968d576464041d49b39 (patch)
parentff3495052af48f7a2bf7961b131dc9e161dae19c (diff)
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 <>
1 files changed, 4 insertions, 1 deletions
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)