Re: [PATCH 1/1] ip_vs_sip_fill_param() BUG: bad check of return value

[Simon Horman <horms@verge.net.au>]

On Thu, Apr 25, 2013 at 11:13:35AM +0200, Hans Schillstrom wrote:
> 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()
> 
> v2 return -EINVAL on Zero return from ct_sip_get_header()
>    Thanks Julian.
> 
> 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>

I would like to wait for feedback from Julian before applying this.
But in the mean time I have a question: this bug has been around for a while,
right?

> ---
>  net/netfilter/ipvs/ip_vs_pe_sip.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_pe_sip.c b/net/netfilter/ipvs/ip_vs_pe_sip.c
> index 00cc024..f2c9d65 100644
> --- a/net/netfilter/ipvs/ip_vs_pe_sip.c
> +++ b/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;
> -- 
> 1.7.11.7
> 
> --
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