Re: Fw: [Bug 46131] New: 32-bit read from uninitialized memory in __ip_select_ident since 3.6-rc2

[Eric Dumazet <eric.dumazet@gmail.com>]

On Mon, 2012-08-20 at 18:24 +0200, Eric Dumazet wrote:
> On Mon, 2012-08-20 at 09:03 -0700, Stephen Hemminger wrote:
> > 
> > Begin forwarded message:
> > 
> > Date: Sat, 18 Aug 2012 09:49:45 +0000 (UTC)
> > From: bugzilla-daemon@bugzilla.kernel.org
> > To: shemminger@linux-foundation.org
> > Subject: [Bug 46131] New: 32-bit read from uninitialized memory in __ip_select_ident since 3.6-rc2
> > 
> > 
> > https://bugzilla.kernel.org/show_bug.cgi?id=46131
> > 
> >            Summary: 32-bit read from uninitialized memory in
> >                     __ip_select_ident since 3.6-rc2
> >            Product: Networking
> >            Version: 2.5
> >     Kernel Version: 3.6-rc2
> >           Platform: All
> >         OS/Version: Linux
> >               Tree: Mainline
> >             Status: NEW
> >           Severity: normal
> >           Priority: P1
> >          Component: IPV4
> >         AssignedTo: shemminger@linux-foundation.org
> >         ReportedBy: casteyde.christian@free.fr
> >         Regression: Yes
> > 
> > 
> > Slacware64 current
> > Intel Core i7
> > 6GB RAM
> > 
> > Since 3.6-rc2 (this is a regression from 3.6-rc1), I get the following warning
> > when I ping a host:
> > 
> > WARNING: kmemcheck: Caught 32-bit read from uninitialized memory
> > (ffff8801c3f79460)
> > 00000000030380ab00000000450000482881000080118ebbc0a8010bc0a8010d
> >  u u u u i i i i i i i i i i i i i i i i i i i i i i i i i i i i
> >  ^
> > Pid: 5836, comm: udev-acl.ck Not tainted 3.6.0-rc2 #3 Acer Aspire 7750G/JE70_HR
> > RIP: 0010:[<ffffffff81697ed2>]  [<ffffffff81697ed2>]
> > __ip_select_ident+0x22/0x120
> > RSP: 0000:ffff8801c7e035e0  EFLAGS: 00010282
> > RAX: ffff88018194ab00 RBX: ffff88018b454700 RCX: 0000000000000040
> > RDX: 0000000000000001 RSI: ffff8801c7e035ec RDI: ffff8801c3f79450
> > RBP: ffff8801c7e03620 R08: ffff8801c54a8238 R09: 0000000000000000
> > R10: ffff8801c7e03770 R11: 0000000000000050 R12: ffff8801c3f79450
> > R13: 0000000000000000 R14: ffff88018db74a80 R15: ffff8801c3f79450
> > FS:  00007f0692dfb740(0000) GS:ffff8801c7e00000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: ffff8801c6b06a88 CR3: 00000001a9ae5000 CR4: 00000000000407f0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000ffff4ff0 DR7: 0000000000000400
> >  [<ffffffff816a2aa8>] __ip_make_skb+0x2f8/0x3c0
> >  [<ffffffff816a2bd7>] ip_push_pending_frames+0x17/0x30
> >  [<ffffffff816d16be>] icmp_push_reply+0xee/0x120
> >  [<ffffffff816d1b95>] icmp_send+0x4a5/0xb10
> >  [<ffffffff816ce5b8>] __udp4_lib_rcv+0x568/0x920
> >  [<ffffffff816ce985>] udp_rcv+0x15/0x20
> >  [<ffffffff8169b0d7>] ip_local_deliver_finish+0x107/0x460
> >  [<ffffffff8169b6f8>] ip_local_deliver+0x88/0x90
> >  [<ffffffff8169ab10>] ip_rcv_finish+0x120/0x5e0
> >  [<ffffffff8169b919>] ip_rcv+0x219/0x2b0
> >  [<ffffffff8164de82>] __netif_receive_skb+0x742/0x9b0
> >  [<ffffffff8164ef68>] netif_receive_skb+0x28/0x1e0
> >  [<ffffffff817a2de5>] ieee80211_deliver_skb.isra.28+0xa5/0x220
> >  [<ffffffff817a3e87>] ieee80211_rx_handlers+0xf27/0x2380
> >  [<ffffffff817a55e7>] ieee80211_prepare_and_rx_handle+0x307/0x8b0
> >  [<ffffffff817a620e>] ieee80211_rx+0x67e/0xce0
> >  [<ffffffff814b819c>] ath_rx_tasklet+0xc9c/0x1350
> >  [<ffffffff814b6024>] ath9k_tasklet+0xe4/0x140
> >  [<ffffffff810784ec>] tasklet_action+0x6c/0xe0
> >  [<ffffffff81078e5a>] __do_softirq+0xba/0x180
> >  [<ffffffff817e32dc>] call_softirq+0x1c/0x30
> >  [<ffffffff8103a4ed>] do_softirq+0x7d/0xb0
> >  [<ffffffff81079276>] irq_exit+0x96/0xc0
> >  [<ffffffff81039f8e>] do_IRQ+0x5e/0xd0
> >  [<ffffffff817e18ac>] ret_from_intr+0x0/0x13
> >  [<ffffffffffffffff>] 0xffffffffffffffff
> 
> Thanks for the report, I am testing a patch.
> 

Christian, are you sure its a 3.6.-rc2 regression, because I believe its
an old bug...

Could you test following fix ?

(ip_select_ident() must be called _after_ iph->daddr is set)


diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 147ccc3..c196d74 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1338,10 +1338,10 @@ struct sk_buff *__ip_make_skb(struct sock *sk,
 	iph->ihl = 5;
 	iph->tos = inet->tos;
 	iph->frag_off = df;
-	ip_select_ident(iph, &rt->dst, sk);
 	iph->ttl = ttl;
 	iph->protocol = sk->sk_protocol;
 	ip_copy_addrs(iph, fl4);
+	ip_select_ident(iph, &rt->dst, sk);
 
 	if (opt) {
 		iph->ihl += opt->optlen>>2;