[PATCH] USB gadget rndis: fix bug skb_push function may return an unaligned pointer bug

[PATCH] USB gadget rndis: fix bug skb_push function may return an unaligned pointer bug

[Wu, Bryan]

USB gadget rndis: skb_push function may return a pointer which is not
aligned as required by struct rndis_packet_msg_type.

Signed-off-by: Bryan Wu <bryan.wu@analog.com>
---
 drivers/usb/gadget/rndis.c |   19 ++++++++++++-------
 1 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/gadget/rndis.c b/drivers/usb/gadget/rndis.c
index 6ec8cf1..48335bb 100644
--- a/drivers/usb/gadget/rndis.c
+++ b/drivers/usb/gadget/rndis.c
@@ -1211,18 +1211,23 @@ int rndis_set_param_medium (u8 configNr, u32 medium, u32 speed)
 	return 0;
 }
 
+/* The pointer of header is not aligned, it will cause alignment exception.
+ * Use a temporary variable to avoid it.
+ */
 void rndis_add_hdr (struct sk_buff *skb)
 {
-	struct rndis_packet_msg_type	*header;
+	void *buf;
+	struct rndis_packet_msg_type *header;
 
 	if (!skb)
 		return;
-	header = (void *) skb_push (skb, sizeof *header);
-	memset (header, 0, sizeof *header);
-	header->MessageType = __constant_cpu_to_le32(REMOTE_NDIS_PACKET_MSG);
-	header->MessageLength = cpu_to_le32(skb->len);
-	header->DataOffset = __constant_cpu_to_le32 (36);
-	header->DataLength = cpu_to_le32(skb->len - sizeof *header);
+	buf = (void *) skb_push (skb, sizeof *header);
+	memset (buf, 0, sizeof *header);
+	header = (struct rndis_packet_msg_type *)buf;
+	put_unaligned(__constant_cpu_to_le32(REMOTE_NDIS_PACKET_MSG), &header->MessageType);
+	put_unaligned(cpu_to_le32(skb->len), &header->MessageLength);
+	put_unaligned(__constant_cpu_to_le32(36), &header->DataOffset);
+	put_unaligned(cpu_to_le32(skb->len - sizeof *header), &header->DataLength);
 }
 
 void rndis_free_response (int configNr, u8 *buf)
-- 
1.5.0.5

Re: [PATCH] USB gadget rndis: fix bug skb_push function may return an unaligned pointer bug

[David Brownell]

On Tuesday 03 April 2007 11:28 pm, Wu, Bryan wrote:
> USB gadget rndis: skb_push function may return a pointer which is not
> aligned as required by struct rndis_packet_msg_type.

Can you instead try to update the declaration of that struct
so that it's "__attribute__((packed))"?  That's less invasive,
and will address similar issues elsewhere ...

- Dave

Re: [PATCH] USB gadget rndis: fix bug skb_push function may return an unaligned pointer bug

[Wu, Bryan]

On Thu, 2007-04-05 at 14:29 -0700, David Brownell wrote:
> On Tuesday 03 April 2007 11:28 pm, Wu, Bryan wrote:
> > USB gadget rndis: skb_push function may return a pointer which is not
> > aligned as required by struct rndis_packet_msg_type.
> 
> Can you instead try to update the declaration of that struct
> so that it's "__attribute__((packed))"?  That's less invasive,
> and will address similar issues elsewhere ...
> 
> - Dave

OK, Jie and Roy will try to use this __attribute__ method and test it on
blackfin platform. Sorry for missing their "Signed-off-by". I will
resend a patch later for review.

Thanks
-Bryan

[PATCH] USB gadget rndis: fix struct rndis_packet_msg_type unaligned bug

[Wu, Bryan]

[PATCH] usb gadget rndis: 
skb_push function may return a pointer which is not aligned as required
by struct rndis_packet_msg_type. Using attribute trick to fix this bug.

Signed-off-by: Roy Huang <roy.huang@analog.com>
Signed-off-by: Jie Zhang <jie.zhang@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>
---
 drivers/usb/gadget/rndis.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/usb/gadget/rndis.h b/drivers/usb/gadget/rndis.h
index 4c3c725..397b149 100644
--- a/drivers/usb/gadget/rndis.h
+++ b/drivers/usb/gadget/rndis.h
@@ -195,7 +195,7 @@ struct rndis_packet_msg_type
 	__le32	PerPacketInfoLength;
 	__le32	VcHandle;
 	__le32	Reserved;
-};
+} __attribute__ ((packed));
 
 struct rndis_config_parameter
 {
-- 
1.5.0.5