W dniu 02.03.2015 o 23:03, Bin Liu pisze:
Hi,
On Mon, Feb 23, 2015 at 9:02 AM, Andrzej Pietrasiewicz
<andrzej.p@xxxxxxxxxxx> wrote:
Non-standard requests can encode the actual interface number in a
non-standard way. For example composite_setup() assumes
that it is w_index && 0xFF, but the printer function encodes the interface
number in a context-dependet way (either w_index or w_index >> 8).
This can lead to such requests being directed to wrong functions.
This patch adds req_match() method to usb_function. Its purpose is to
verify that a given request can be handled by a given function.
If any function within a configuration provides the method and it returns
true, then it is assumed that the right function is found.
If a function uses req_match(), it should try as hard as possible to
determine if the request is meant for it.
If no functions in a configuration provide req_match or none of them
returns true, then fall back to the usual approach.
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxx>
---
drivers/usb/gadget/composite.c | 7 ++++++-
include/linux/usb/composite.h | 3 +++
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 9fb9231..07cee80 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -1758,6 +1758,11 @@ unknown:
* take such requests too, if that's ever needed: to work
* in config 0, etc.
*/
+ list_for_each_entry(f, &cdev->config->functions, list)
+ if (f->req_match && f->req_match(f, ctrl))
+ break;
In this loop, if f->req_match is NULL, or f->req_match() returns
false, f becomes non-NULL at the end of the loop, which causes kernel
panic later.
+ if (&f->list != &cdev->config->functions)
+ goto try_fun_setup;
The following change fixes it.
+ list_for_each_entry(f, &cdev->config->functions, list)
+ if (f->req_match && f->req_match(f, ctrl))
+ goto try_fun_setup;
+
+ f = NULL;
+
Right. Thanks!
AP
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