lkml.org 
[lkml]   [2008]   [May]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [patch 20/37] {nfnetlink, ip, ip6}_queue: fix skb_over_panic when enlarging packets
Gustavo Guillermo Perez wrote:
> El Martes, 13 de Mayo de 2008, Greg KH escribió:
>> On Wed, May 14, 2008 at 01:45:15AM +0200, Arnaud Ebalard wrote:
>>> Hi,
>>>
>>> Greg KH <gregkh@suse.de> writes:
>>>> 2.6.25-stable review patch. If anyone has any objections, please let
>>>> us know.
>>> Sorry for the noise, but for those who missed one of the latest post on
>>> the topic on netdev, I should add that the bug is also in 2.6.24.4 (even
>>> if it's probably too late for that poor guy :-( ).
>> Sorry, yes, we are no longer doing 2.6.24-stable releases.
>
> the fix will be available in 2.6.25.4 ?

Yes. This is the patch against the latest 2.6.24.x release in case
someone needs it. Not sure anymore if it differs from the 2.6.25
version.


commit 431e3757dbafdad741ef7d9bdaa2fca7fce3d5cc
Author: Arnaud Ebalard <arno@natisbad.org>
Date: Tue May 6 13:03:59 2008 +0200

[NETFILTER]: {nfnetlink,ip,ip6}_queue: fix skb_over_panic when enlarging packets

Upstream commit 9a732ed6d:

While reinjecting *bigger* modified versions of IPv6 packets using
libnetfilter_queue, things work fine on a 2.6.24 kernel (2.6.22 too)
but I get the following on recents kernels (2.6.25, trace below is
against today's net-2.6 git tree):

skb_over_panic: text:c04fddb0 len:696 put:632 head:f7592c00 data:f7592c00 tail:0xf7592eb8 end:0xf7592e80 dev:eth0
------------[ cut here ]------------
invalid opcode: 0000 [#1] PREEMPT
Process sendd (pid: 3657, ti=f6014000 task=f77c31d0 task.ti=f6014000)
Stack: c071e638 c04fddb0 000002b8 00000278 f7592c00 f7592c00 f7592eb8 f7592e80
f763c000 f6bc5200 f7592c40 f6015c34 c04cdbfc f6bc5200 00000278 f6015c60
c04fddb0 00000020 f72a10c0 f751b420 00000001 0000000a 000002b8 c065582c
Call Trace:
[<c04fddb0>] ? nfqnl_recv_verdict+0x1c0/0x2e0
[<c04cdbfc>] ? skb_put+0x3c/0x40
[<c04fddb0>] ? nfqnl_recv_verdict+0x1c0/0x2e0
[<c04fd115>] ? nfnetlink_rcv_msg+0xf5/0x160
[<c04fd03e>] ? nfnetlink_rcv_msg+0x1e/0x160
[<c04fd020>] ? nfnetlink_rcv_msg+0x0/0x160
[<c04f8ed7>] ? netlink_rcv_skb+0x77/0xa0
[<c04fcefc>] ? nfnetlink_rcv+0x1c/0x30
[<c04f8c73>] ? netlink_unicast+0x243/0x2b0
[<c04cfaba>] ? memcpy_fromiovec+0x4a/0x70
[<c04f9406>] ? netlink_sendmsg+0x1c6/0x270
[<c04c8244>] ? sock_sendmsg+0xc4/0xf0
[<c011970d>] ? set_next_entity+0x1d/0x50
[<c0133a80>] ? autoremove_wake_function+0x0/0x40
[<c0118f9e>] ? __wake_up_common+0x3e/0x70
[<c0342fbf>] ? n_tty_receive_buf+0x34f/0x1280
[<c011d308>] ? __wake_up+0x68/0x70
[<c02cea47>] ? copy_from_user+0x37/0x70
[<c04cfd7c>] ? verify_iovec+0x2c/0x90
[<c04c837a>] ? sys_sendmsg+0x10a/0x230
[<c011967a>] ? __dequeue_entity+0x2a/0xa0
[<c011970d>] ? set_next_entity+0x1d/0x50
[<c0345397>] ? pty_write+0x47/0x60
[<c033d59b>] ? tty_default_put_char+0x1b/0x20
[<c011d2e9>] ? __wake_up+0x49/0x70
[<c033df99>] ? tty_ldisc_deref+0x39/0x90
[<c033ff20>] ? tty_write+0x1a0/0x1b0
[<c04c93af>] ? sys_socketcall+0x7f/0x260
[<c0102ff9>] ? sysenter_past_esp+0x6a/0x91
[<c05f0000>] ? snd_intel8x0m_probe+0x270/0x6e0
=======================
Code: 00 00 89 5c 24 14 8b 98 9c 00 00 00 89 54 24 0c 89 5c 24 10 8b 40 50 89 4c 24 04 c7 04 24 38 e6 71 c0 89 44 24 08 e8 c4 46 c5 ff <0f> 0b eb fe 55 89 e5 56 89 d6 53 89 c3 83 ec 0c 8b 40 50 39 d0
EIP: [<c04ccdfc>] skb_over_panic+0x5c/0x60 SS:ESP 0068:f6015bf8


Looking at the code, I ended up in nfq_mangle() function (called by
nfqnl_recv_verdict()) which performs a call to skb_copy_expand() due to
the increased size of data passed to the function. AFAICT, it should ask
for 'diff' instead of 'diff - skb_tailroom(e->skb)'. Because the
resulting sk_buff has not enough space to support the skb_put(skb, diff)
call a few lines later, this results in the call to skb_over_panic().

The patch below asks for allocation of a copy with enough space for
mangled packet and the same amount of headroom as old sk_buff. While
looking at how the regression appeared (e2b58a67), I noticed the same
pattern in ipq_mangle_ipv6() and ipq_mangle_ipv4(). The patch corrects
those locations too.

Tested with bigger reinjected IPv6 packets (nfqnl_mangle() path), things
are ok (2.6.25 and today's net-2.6 git tree).

Signed-off-by: Arnaud Ebalard <arno@natisbad.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/netfilter/ip_queue.c b/net/ipv4/netfilter/ip_queue.c
index 16d0fb3..f821a9b 100644
--- a/net/ipv4/netfilter/ip_queue.c
+++ b/net/ipv4/netfilter/ip_queue.c
@@ -349,9 +349,8 @@ ipq_mangle_ipv4(ipq_verdict_msg_t *v, struct ipq_queue_entry *e)
if (v->data_len > 0xFFFF)
return -EINVAL;
if (diff > skb_tailroom(e->skb)) {
- nskb = skb_copy_expand(e->skb, 0,
- diff - skb_tailroom(e->skb),
- GFP_ATOMIC);
+ nskb = skb_copy_expand(e->skb, skb_headroom(e->skb),
+ diff, GFP_ATOMIC);
if (!nskb) {
printk(KERN_WARNING "ip_queue: error "
"in mangle, dropping packet\n");
diff --git a/net/ipv6/netfilter/ip6_queue.c b/net/ipv6/netfilter/ip6_queue.c
index 710a04f..b9db6d9 100644
--- a/net/ipv6/netfilter/ip6_queue.c
+++ b/net/ipv6/netfilter/ip6_queue.c
@@ -346,9 +346,8 @@ ipq_mangle_ipv6(ipq_verdict_msg_t *v, struct ipq_queue_entry *e)
if (v->data_len > 0xFFFF)
return -EINVAL;
if (diff > skb_tailroom(e->skb)) {
- nskb = skb_copy_expand(e->skb, 0,
- diff - skb_tailroom(e->skb),
- GFP_ATOMIC);
+ nskb = skb_copy_expand(e->skb, skb_headroom(e->skb),
+ diff, GFP_ATOMIC);
if (!nskb) {
printk(KERN_WARNING "ip6_queue: OOM "
"in mangle, dropping packet\n");
diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index 7c3646c..d5fab38 100644
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -627,9 +627,8 @@ nfqnl_mangle(void *data, int data_len, struct nfqnl_queue_entry *e)
if (data_len > 0xFFFF)
return -EINVAL;
if (diff > skb_tailroom(e->skb)) {
- nskb = skb_copy_expand(e->skb, 0,
- diff - skb_tailroom(e->skb),
- GFP_ATOMIC);
+ nskb = skb_copy_expand(e->skb, skb_headroom(e->skb),
+ diff, GFP_ATOMIC);
if (!nskb) {
printk(KERN_WARNING "nf_queue: OOM "
"in mangle, dropping packet\n");
\
 
 \ /
  Last update: 2008-05-14 19:11    [W:1.788 / U:0.040 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site