RE: [PATCH v2 2/5] staging: r8188eu: cast to restricted __be32

[David Laight <David.Laight@ACULAB.COM>]

From: Larry Finger
> Sent: 20 August 2021 22:45
> 
> On 8/19/21 3:17 AM, Aakash Hemadri wrote:
> > Fix sparse warning:
> >> rtw_br_ext.c:836:54: warning: cast to restricted __be32
> >
> > Unnecessary double cast, remove them.
> >
> > Signed-off-by: Aakash Hemadri <aakashhemadri123@gmail.com>
> > ---
> >   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 404fa8904e47..6a0462ce6230 100644
> > --- a/drivers/staging/r8188eu/core/rtw_br_ext.c
> > +++ b/drivers/staging/r8188eu/core/rtw_br_ext.c
> > @@ -671,7 +671,7 @@ void dhcp_flag_bcast(struct adapter *priv, struct sk_buff *skb)
> >   				    (udph->dest == __constant_htons(SERVER_PORT))) { /*  DHCP request */
> >   					struct dhcpMessage *dhcph =
> >   						(struct dhcpMessage *)((size_t)udph + sizeof(struct udphdr));
> > -					u32 cookie = be32_to_cpu((__be32)dhcph->cookie);
> > +					u32 cookie = dhcph->cookie;
> >
> >   					if (cookie == DHCP_MAGIC) { /*  match magic word */
> >   						if (!(dhcph->flags & htons(BROADCAST_FLAG))) {
> >
> 
> This patch is wrong. All the documentation I could find tells me that the
> multi-byte entries in dhcph are big-endian, thus the new line should read:
> 
> 					u32 cookie = be32_to_cpu(dhcph->cookie);

Modulo anything that really means it should get_unaligned_be32().

	David

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