Since the beginning of time, struct usb_ep::maxpacket was a bitfield,
and when new 16-bit members were added, the convention was followed:
1da177e4c3f41 (Linus Torvalds 2005-04-16 236) unsigned maxpacket:16;
e117e742d3106 (Robert Baldyga 2013-12-13 237) unsigned maxpacket_limit:16;
a59d6b91cbca5 (Tatyana Brokhman 2011-06-28 238) unsigned max_streams:16;
However, there is no need for this as a simple u16 can be used instead,
simplifying the struct and the resulting compiler binary output. Switch
to u16 for all three, and rearrange struct slightly to minimize holes.
No change in the final size of the struct results; the 2 byte gap is
just moved to the end, as seen with pahole:
- /* XXX 2 bytes hole, try to pack */
...
/* size: 72, cachelines: 2, members: 15 */
...
+ /* padding: 2 */
Changing this simplifies future introspection[1] of maxpacket's type during
allocations:
drivers/usb/gadget/function/f_tcm.c:330:24: error: 'typeof' applied to a bit-field
330 | fu->cmd.buf = kmalloc(fu->ep_out->maxpacket, GFP_KERNEL);
Link: https://lore.kernel.org/all/202407090928.6UaOAZAJ-lkp@xxxxxxxxx [1]
Signed-off-by: Kees Cook <kees@xxxxxxxxxx>
---
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: linux-usb@xxxxxxxxxxxxxxx
---
include/linux/usb/gadget.h | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 56dda8e1562d..df33333650a0 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -229,18 +229,18 @@ struct usb_ep {
const char *name;
const struct usb_ep_ops *ops;
+ const struct usb_endpoint_descriptor *desc;
+ const struct usb_ss_ep_comp_descriptor *comp_desc;
struct list_head ep_list;
struct usb_ep_caps caps;
bool claimed;
bool enabled;
- unsigned maxpacket:16;
- unsigned maxpacket_limit:16;
- unsigned max_streams:16;
unsigned mult:2;
unsigned maxburst:5;
u8 address;
- const struct usb_endpoint_descriptor *desc;
- const struct usb_ss_ep_comp_descriptor *comp_desc;
+ u16 maxpacket;
+ u16 maxpacket_limit;
+ u16 max_streams;
};
/*-------------------------------------------------------------------------*/
--
2.34.1
