diff options
| author | Alan Stern <stern@rowland.harvard.edu> | 2005-11-03 11:44:49 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2006-01-04 13:48:29 -0800 |
| commit | 6912354a895fcd234155273fe8838a0d83259a9b (patch) | |
| tree | 6dca4969dda3fb177c62f18b12bfb6d2be4bb567 | |
| parent | 959eea2191e8d74b16ef019b0f4bf875c14f4547 (diff) | |
[PATCH] USB: EHCI: fix conflation of buf == 0 with len == 0
When the ehci-hcd driver prepares a control URB, it tests for a
zero-length data stage by looking at the transfer_dma value instead of
the transfer_buffer_length. (In fact it does this even for non-control
URBs, which is an additional aspect of the same bug.)
However, under certain circumstances it's possible for transfer_dma to
be 0 while transfer_buffer_length is non-zero. This can happen when a
freshly allocated page (mapped to address 0 and marked Copy-On-Write,
but never written to) is used as the source buffer for an OUT transfer.
This patch (as598) fixes the problem.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | drivers/usb/host/ehci-q.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c index bf03ec0d8ee..9b13bf2fa98 100644 --- a/drivers/usb/host/ehci-q.c +++ b/drivers/usb/host/ehci-q.c @@ -514,18 +514,18 @@ qh_urb_transaction ( qtd->urb = urb; qtd_prev->hw_next = QTD_NEXT (qtd->qtd_dma); list_add_tail (&qtd->qtd_list, head); + + /* for zero length DATA stages, STATUS is always IN */ + if (len == 0) + token |= (1 /* "in" */ << 8); } /* * data transfer stage: buffer setup */ - if (likely (len > 0)) - buf = urb->transfer_dma; - else - buf = 0; + buf = urb->transfer_dma; - /* for zero length DATA stages, STATUS is always IN */ - if (!buf || is_input) + if (is_input) token |= (1 /* "in" */ << 8); /* else it's already initted to "out" pid (0 << 8) */ @@ -572,7 +572,7 @@ qh_urb_transaction ( * control requests may need a terminating data "status" ack; * bulk ones may need a terminating short packet (zero length). */ - if (likely (buf != 0)) { + if (likely (urb->transfer_buffer_length != 0)) { int one_more = 0; if (usb_pipecontrol (urb->pipe)) { |