ipvs: ip_vs_sip_fill_param() BUG: bad check of return value

The reason for this patch is crash in kmemdup
caused by returning from get_callid with uniialized
matchoff and matchlen.

Removing Zero check of matchlen since it's done by ct_sip_get_header()

BUG: unable to handle kernel paging request at ffff880457b5763f
IP: [<ffffffff810df7fc>] kmemdup+0x2e/0x35
PGD 27f6067 PUD 0
Oops: 0000 [#1] PREEMPT SMP
Modules linked in: xt_state xt_helper nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_mangle xt_connmark xt_conntrack ip6_tables nf_conntrack_ftp ip_vs_ftp nf_nat xt_tcpudp iptable_mangle xt_mark ip_tables x_tables ip_vs_rr ip_vs_lblcr ip_vs_pe_sip ip_vs nf_conntrack_sip nf_conntrack bonding igb i2c_algo_bit i2c_core
CPU 5
Pid: 0, comm: swapper/5 Not tainted 3.9.0-rc5+ #5                  /S1200KP
RIP: 0010:[<ffffffff810df7fc>]  [<ffffffff810df7fc>] kmemdup+0x2e/0x35
RSP: 0018:ffff8803fea03648  EFLAGS: 00010282
RAX: ffff8803d61063e0 RBX: 0000000000000003 RCX: 0000000000000003
RDX: 0000000000000003 RSI: ffff880457b5763f RDI: ffff8803d61063e0
RBP: ffff8803fea03658 R08: 0000000000000008 R09: 0000000000000011
R10: 0000000000000011 R11: 00ffffffff81a8a3 R12: ffff880457b5763f
R13: ffff8803d67f786a R14: ffff8803fea03730 R15: ffffffffa0098e90
FS:  0000000000000000(0000) GS:ffff8803fea00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff880457b5763f CR3: 0000000001a0c000 CR4: 00000000001407e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process swapper/5 (pid: 0, threadinfo ffff8803ee18c000, task ffff8803ee18a480)
Stack:
 ffff8803d822a080 000000000000001c ffff8803fea036c8 ffffffffa000937a
 ffffffff81f0d8a0 000000038135fdd5 ffff880300000014 ffff880300110000
 ffffffff150118ac ffff8803d7e8a000 ffff88031e0118ac 0000000000000000
Call Trace:
 <IRQ>

 [<ffffffffa000937a>] ip_vs_sip_fill_param+0x13a/0x187 [ip_vs_pe_sip]
 [<ffffffffa007b209>] ip_vs_sched_persist+0x2c6/0x9c3 [ip_vs]
 [<ffffffff8107dc53>] ? __lock_acquire+0x677/0x1697
 [<ffffffff8100972e>] ? native_sched_clock+0x3c/0x7d
 [<ffffffff8100972e>] ? native_sched_clock+0x3c/0x7d
 [<ffffffff810649bc>] ? sched_clock_cpu+0x43/0xcf
 [<ffffffffa007bb1e>] ip_vs_schedule+0x181/0x4ba [ip_vs]
...
Signed-off-by: Hans Schillstrom <hans@schillstrom.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netfilter/ipvs/ip_vs_pe_sip.c

@@ -37,14 +37,10 @@ static int get_callid(const char *dptr, unsigned int dataoff,
 		if (ret > 0)
 			break;
 		if (!ret)
-			return 0;
+			return -EINVAL;
 		dataoff += *matchoff;
 	}
 
-	/* Empty callid is useless */
-	if (!*matchlen)
-		return -EINVAL;
-
 	/* Too large is useless */
 	if (*matchlen > IP_VS_PEDATA_MAXLEN)
 		return -EINVAL;