[PATCH] staging: r8188eu: Fix PPPoE tag insertion on big endian systems

From: Guenter Roeck
Date: Fri Apr 01 2022 - 11:51:03 EST

In __nat25_add_pppoe_tag(), the tag length is read from the tag data
structure. The value is kept in network format, but read as raw value.
With -Warray-bounds, this results in the following gcc error/warning
when building the driver on a big endian system such as alpha.

In function '__nat25_add_pppoe_tag',
inlined from 'nat25_db_handle' at
arch/alpha/include/asm/string.h:22:16: error:
'__builtin_memcpy' forming offset [40, 2051] is out of the bounds
[0, 40] of object 'tag_buf' with type 'unsigned char[40]'

Add the missing ntohs().

Fixes: 15865124feed ("staging: r8188eu: introduce new core dir for RTL8188eu driver")
Cc: Phillip Potter <phil@xxxxxxxxxxxxxxxx>
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
drivers/staging/r8188eu/core/rtw_br_ext.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/r8188eu/core/rtw_br_ext.c b/drivers/staging/r8188eu/core/rtw_br_ext.c
index d68611ef22f8..31bcd495ec04 100644
--- a/drivers/staging/r8188eu/core/rtw_br_ext.c
+++ b/drivers/staging/r8188eu/core/rtw_br_ext.c
@@ -70,7 +70,7 @@ static int __nat25_add_pppoe_tag(struct sk_buff *skb, struct pppoe_tag *tag)
struct pppoe_hdr *ph = (struct pppoe_hdr *)(skb->data + ETH_HLEN);
int data_len;

- data_len = tag->tag_len + TAG_HDR_LEN;
+ data_len = htons(tag->tag_len) + TAG_HDR_LEN;
if (skb_tailroom(skb) < data_len)
return -1;