[patch 13/76] IPCONFIG: The kernel gets no IP from some DHCP servers

[Chris Wright]

-stable review patch.  If anyone has any objections, please let us know.
---------------------

From: Stephen Hemminger <shemminger@xxxxxxxxxxxxxxxxxxxx>

Upstream commit: dea75bdfa57f75a7a7ec2961ec28db506c18e5db

From: Stephen Hemminger <shemminger@xxxxxxxxxxxxxxxxxxxx>

Based upon a patch by Marcel Wappler:

   This patch fixes a DHCP issue of the kernel: some DHCP servers
   (i.e.  in the Linksys WRT54Gv5) are very strict about the contents
   of the DHCPDISCOVER packet they receive from clients.

   Table 5 in RFC2131 page 36 requests the fields 'ciaddr' and
   'siaddr' MUST be set to '0'.  These DHCP servers ignore Linux
   kernel's DHCP discovery packets with these two fields set to
   '255.255.255.255' (in contrast to popular DHCP clients, such as
   'dhclient' or 'udhcpc').  This leads to a not booting system.

Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>

---
 net/ipv4/ipconfig.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/ipv4/ipconfig.c
+++ b/net/ipv4/ipconfig.c
@@ -739,9 +739,9 @@ static void __init ic_bootp_send_if(stru
 		printk("Unknown ARP type 0x%04x for device %s\n", dev->type, dev->name);
 		b->htype = dev->type; /* can cause undefined behavior */
 	}
+
+	/* server_ip and your_ip address are both already zero per RFC2131 */
 	b->hlen = dev->addr_len;
-	b->your_ip = NONE;
-	b->server_ip = NONE;
 	memcpy(b->hw_addr, dev->dev_addr, dev->addr_len);
 	b->secs = htons(jiffies_diff / HZ);
 	b->xid = d->xid;

-- 
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