| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <1320191893.4728.13.camel@edumazet-laptop>
Date: Wed, 02 Nov 2011 00:58:13 +0100
From: Eric Dumazet <eric.dumazet@...il.com>
To: Misha Labjuk <spiked.yar@...il.com>,
David Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org
Subject: Re: PROBLEM: pppol2tp over pppoe NULL pointer dereference
Le mercredi 02 novembre 2011 à 01:00 +0300, Misha Labjuk a écrit :
> pppol2tp over pppoe NULL pointer dereference
>
> Kernel panic after establishing pppol2tp tunnel over pppoe connection.
> Get panic in 5-15 min with 10 mbit/s data transfer speed.
> pppoe and pppol2tp connections stable separately.
>
> Linux version 3.1.0 (user@...t) (gcc version 4.6.1 (Gentoo 4.6.1-r1
> p1.0, pie-0.4.5) ) #1 SMP Mon Oct 31 18:48:18 MSK 2011
>
> [ 151.913193] L2TP core driver, V2.0
> [ 151.974584] L2TP netlink interface
> [ 151.993803] PPPoL2TP kernel driver, V2.0
> [ 437.496670] BUG: unable to handle kernel NULL pointer dereference
> at 0000000000000008
> [ 437.496683] IP: [<ffffffffa03679dc>] l2tp_recv_common+0x4d3/0x621 [l2tp_core]
> [ 437.496691] PGD d7840067 PUD cd4e7067 PMD 0
> [ 437.496697] Oops: 0002 [#1] SMP
> [ 437.496702] CPU 0
> [ 437.496704] Modules linked in: l2tp_ppp l2tp_netlink l2tp_core
> firewire_sbp2 sit tunnel4 netconsole it87 hwmon_vid coretemp pppoe
> pppox ppp_generic slhc ipt_MASQUERADE iptable_nat nf_nat
> nf_conntrack_ipv4 nf_conntrack nf_defrag_ipv4 xt_TCPMSS iptable_mangle
> ip_tables snd_seq_midi snd_emu10k1_synth snd_emux_synth
> snd_seq_virmidi snd_seq_midi_emul snd_seq_dummy snd_seq_oss
> snd_seq_midi_event snd_seq snd_pcm_oss snd_mixer_oss nfsd lockd
> nfs_acl auth_rpcgss sunrpc usb_storage usb_libusual uas usbhid ipv6
> snd_emu10k1 8250_pnp snd_rawmidi snd_hda_codec_realtek snd_ac97_codec
> snd_hda_intel snd_hda_codec uhci_hcd ac97_bus snd_pcm ehci_hcd usbcore
> snd_seq_device snd_timer 8250 snd_util_mem snd_hwdep psmouse snd
> firewire_ohci firewire_core serial_core intel_agp intel_gtt pcspkr
> soundcore r8169 crc_itu_t mii snd_page_alloc processor button
> [ 437.497005]
> [ 437.497005] Pid: 3274, comm: qbittorrent Not tainted 3.1.0 #1
> Gigabyte Technology Co., Ltd. EP45-EXTREME/EP45-EXTREME
> [ 437.497005] RIP: 0010:[<ffffffffa03679dc>] [<ffffffffa03679dc>]
> l2tp_recv_common+0x4d3/0x621 [l2tp_core]
> [ 437.497005] RSP: 0000:ffff88011fc03b90 EFLAGS: 00010296
> [ 437.497005] RAX: 0000000000000000 RBX: ffff8800d79e8200 RCX: ffff88011fc10bd0
> [ 437.497005] RDX: 0000000000000000 RSI: 0000000000004002 RDI: ffff8800d79e8254
> [ 437.497005] RBP: ffff88011fc03be0 R08: 0000000000004002 R09: 0000000000004002
> [ 437.497005] R10: ffff8801091ec87a R11: ffff88011b300000 R12: ffff880118922300
> [ 437.497005] R13: 0000000000000000 R14: ffff8800d79e8254 R15: ffff8800d79e826c
> [ 437.497005] FS: 00007f0ced3e8700(0000) GS:ffff88011fc00000(0000)
> knlGS:0000000000000000
> [ 437.497005] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 437.497005] CR2: 0000000000000008 CR3: 00000000c8811000 CR4: 00000000000406f0
> [ 437.497005] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 437.497005] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> [ 437.497005] Process qbittorrent (pid: 3274, threadinfo
> ffff8800c9906000, task ffff8800db999200)
> [ 437.497005] Stack:
> [ 437.497005] ffff88011fc03bb0 ffff8801091ec872 ffff8800d79e8240
> 0000052000000520
> [ 437.497005] ffff88011fc03be0 ffff8800d7844e00 ffff880119099200
> ffff8801091ec872
> [ 437.497005] ffff8800db8b6400 00000000000050cd ffff88011fc03c60
> ffffffffa0367e65
> [ 437.497005] Call Trace:
> [ 437.497005] <IRQ>
> [ 437.497005] [<ffffffffa0367e65>] l2tp_udp_encap_recv+0x33b/0x3e6 [l2tp_core]
> [ 437.497005] [<ffffffffa0377d96>] ? pppol2tp_setsockopt+0x2e0/0x2e0
> [l2tp_ppp]
> [ 437.497005] [<ffffffffa030640c>] ? ipv4_confirm+0x17e/0x198
> [nf_conntrack_ipv4]
> [ 437.497005] [<ffffffffa0377d96>] ? pppol2tp_setsockopt+0x2e0/0x2e0
> [l2tp_ppp]
> [ 437.497005] [<ffffffff812eb32b>] udp_queue_rcv_skb+0xee/0x2ce
> [ 437.497005] [<ffffffff812ebba3>] __udp4_lib_rcv+0x2d2/0x536
> [ 437.497005] [<ffffffff812cb046>] ? ip_rcv_finish+0x29a/0x29a
> [ 437.497005] [<ffffffff812ebe1c>] udp_rcv+0x15/0x17
> [ 437.497005] [<ffffffff812cb165>] ip_local_deliver_finish+0x11f/0x1c7
> [ 437.497005] [<ffffffff812cb361>] ip_local_deliver+0x75/0x7c
> [ 437.497005] [<ffffffff812cb023>] ip_rcv_finish+0x277/0x29a
> [ 437.497005] [<ffffffff812cb5a1>] ip_rcv+0x239/0x260
> [ 437.497005] [<ffffffff812a46cd>] ? napi_skb_finish+0x21/0x38
> [ 437.497005] [<ffffffff812a3adb>] __netif_receive_skb+0x430/0x462
> [ 437.497005] [<ffffffff8102342f>] ? update_curr+0x53/0x89
> [ 437.497005] [<ffffffff812a3b9d>] process_backlog+0x90/0x151
> [ 437.497005] [<ffffffff812a3e6a>] net_rx_action+0x9e/0x171
> [ 437.497005] [<ffffffff810344b0>] __do_softirq+0x93/0x129
> [ 437.497005] [<ffffffff8133034c>] call_softirq+0x1c/0x30
> [ 437.497005] [<ffffffff8100351c>] do_softirq+0x33/0x6b
> [ 437.497005] [<ffffffff8103470b>] irq_exit+0x52/0xac
> [ 437.497005] [<ffffffff81003251>] do_IRQ+0x98/0xaf
> [ 437.497005] [<ffffffff8132eb6b>] common_interrupt+0x6b/0x6b
> [ 437.497005] <EOI>
> [ 437.497005] [<ffffffff8132f17b>] ? system_call_fastpath+0x16/0x1b
> [ 437.497005] Code: 6c e8 57 03 fc e0 e9 22 01 00 00 ff 4b 50 4c 89
> f7 49 8b 14 24 49 c7 04 24 00 00 00 00 49 8b 44 24 08 49 c7 44 24 08
> 00 00 00 00
> [ 437.497005] 89 42 08 48 89 10 e8 1d 6f fc e0 41 0f b7 54 24 3e 48 8b 43
> [ 437.497005] RIP [<ffffffffa03679dc>] l2tp_recv_common+0x4d3/0x621
> [l2tp_core]
> [ 437.497005] RSP <ffff88011fc03b90>
> [ 437.497005] CR2: 0000000000000008
> [ 437.498126] ---[ end trace 053df4c7c6743d26 ]---
> [ 437.498184] Kernel panic - not syncing: Fatal exception in interrupt
> [ 437.498187] Pid: 3274, comm: qbittorrent Tainted: G D 3.1.0 #1
> [ 437.498189] Call Trace:
> [ 437.498190] <IRQ> [<ffffffff81327c11>] panic+0x8c/0x189
> [ 437.498197] [<ffffffff8100471d>] oops_end+0x81/0x8e
> [ 437.498200] [<ffffffff8132765b>] no_context+0x1fe/0x20d
> [ 437.498203] [<ffffffff81327829>] __bad_area_nosemaphore+0x1bf/0x1e0
> [ 437.498206] [<ffffffff812a5308>] ? dev_hard_start_xmit+0x412/0x51b
> [ 437.498210] [<ffffffff81327858>] bad_area_nosemaphore+0xe/0x10
> [ 437.498213] [<ffffffff8101c858>] do_page_fault+0x175/0x371
> [ 437.498217] [<ffffffff812a1eba>] ? netif_rx+0xc5/0xd0
> [ 437.498281] [<ffffffffa031ee7d>] ?
> ppp_receive_nonmp_frame+0x58f/0x5cf [ppp_generic]
> [ 437.498286] [<ffffffffa0320625>] ? ppp_receive_frame+0x5c1/0x5e2
> [ppp_generic]
> [ 437.498290] [<ffffffff8132ed6f>] page_fault+0x1f/0x30
> [ 437.498293] [<ffffffffa03679dc>] ? l2tp_recv_common+0x4d3/0x621 [l2tp_core]
> [ 437.498298] [<ffffffffa0367e65>] l2tp_udp_encap_recv+0x33b/0x3e6 [l2tp_core]
> [ 437.498302] [<ffffffffa0377d96>] ? pppol2tp_setsockopt+0x2e0/0x2e0
> [l2tp_ppp]
> [ 437.498306] [<ffffffffa030640c>] ? ipv4_confirm+0x17e/0x198
> [nf_conntrack_ipv4]
> [ 437.498310] [<ffffffffa0377d96>] ? pppol2tp_setsockopt+0x2e0/0x2e0
> [l2tp_ppp]
> [ 437.498314] [<ffffffff812eb32b>] udp_queue_rcv_skb+0xee/0x2ce
> [ 437.498317] [<ffffffff812ebba3>] __udp4_lib_rcv+0x2d2/0x536
> [ 437.498321] [<ffffffff812cb046>] ? ip_rcv_finish+0x29a/0x29a
> [ 437.498324] [<ffffffff812ebe1c>] udp_rcv+0x15/0x17
> [ 437.498328] [<ffffffff812cb165>] ip_local_deliver_finish+0x11f/0x1c7
> [ 437.498332] [<ffffffff812cb361>] ip_local_deliver+0x75/0x7c
> [ 437.498391] [<ffffffff812cb023>] ip_rcv_finish+0x277/0x29a
> [ 437.498394] [<ffffffff812cb5a1>] ip_rcv+0x239/0x260
> [ 437.498398] [<ffffffff812a46cd>] ? napi_skb_finish+0x21/0x38
> [ 437.498401] [<ffffffff812a3adb>] __netif_receive_skb+0x430/0x462
> [ 437.498404] [<ffffffff8102342f>] ? update_curr+0x53/0x89
> [ 437.498408] [<ffffffff812a3b9d>] process_backlog+0x90/0x151
>
>
> Software:
> Gnu C 4.6.1
> Gnu make 3.82
> binutils 2.21.1
> openl2tp 1.8-r3
>
> l2tp_recv_common+0x4d3/0x621 is match to
> net/l2tp/l2tp_core.c:429:__skb_unlink(skb, &session->reorder_q);
> skb->next is NULL.
Please try following patch, thanks !
[PATCH] l2tp: handle fragmented skbs in receive path
Modern drivers provide skb with fragments, and L2TP doesnt properly
handles them.
Some bad frames can also trigger panics because of insufficent checks.
Reported-by: Misha Labjuk <spiked.yar@...il.com>
Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
---
net/l2tp/l2tp_core.c | 71 +++++++++++++++++++++++------------------
net/l2tp/l2tp_core.h | 2 -
net/l2tp/l2tp_ip.c | 22 +++++-------
3 files changed, 50 insertions(+), 45 deletions(-)
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 34b2dde..e04d3a3 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -525,11 +525,10 @@ static inline int l2tp_verify_udp_checksum(struct sock *sk,
* after the session-id.
*/
void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
- unsigned char *ptr, unsigned char *optr, u16 hdrflags,
+ int offset, u16 hdrflags,
int length, int (*payload_hook)(struct sk_buff *skb))
{
struct l2tp_tunnel *tunnel = session->tunnel;
- int offset;
u32 ns, nr;
/* The ref count is increased since we now hold a pointer to
@@ -542,14 +541,17 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
/* Parse and check optional cookie */
if (session->peer_cookie_len > 0) {
- if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
+ if (!pskb_may_pull(skb, offset + session->peer_cookie_len) ||
+ memcmp(skb->data + offset,
+ &session->peer_cookie[0],
+ session->peer_cookie_len)) {
PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
"%s: cookie mismatch (%u/%u). Discarding.\n",
tunnel->name, tunnel->tunnel_id, session->session_id);
session->stats.rx_cookie_discards++;
goto discard;
}
- ptr += session->peer_cookie_len;
+ offset += session->peer_cookie_len;
}
/* Handle the optional sequence numbers. Sequence numbers are
@@ -563,10 +565,12 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
L2TP_SKB_CB(skb)->has_seq = 0;
if (tunnel->version == L2TP_HDR_VER_2) {
if (hdrflags & L2TP_HDRFLAG_S) {
- ns = ntohs(*(__be16 *) ptr);
- ptr += 2;
- nr = ntohs(*(__be16 *) ptr);
- ptr += 2;
+ if (!pskb_may_pull(skb, offset + 4))
+ goto discard;
+ ns = ntohs(*(__be16 *) (skb->data + offset));
+ offset += 2;
+ nr = ntohs(*(__be16 *) (skb->data + offset));
+ offset += 2;
/* Store L2TP info in the skb */
L2TP_SKB_CB(skb)->ns = ns;
@@ -577,8 +581,11 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
session->name, ns, nr, session->nr);
}
} else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
- u32 l2h = ntohl(*(__be32 *) ptr);
+ u32 l2h;
+ if (!pskb_may_pull(skb, offset + 4))
+ goto discard;
+ l2h = ntohl(*(__be32 *) (skb->data + offset));
if (l2h & 0x40000000) {
ns = l2h & 0x00ffffff;
@@ -593,7 +600,7 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
}
/* Advance past L2-specific header, if present */
- ptr += session->l2specific_len;
+ offset += session->l2specific_len;
if (L2TP_SKB_CB(skb)->has_seq) {
/* Received a packet with sequence numbers. If we're the LNS,
@@ -647,13 +654,13 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
if (tunnel->version == L2TP_HDR_VER_2) {
/* If offset bit set, skip it. */
if (hdrflags & L2TP_HDRFLAG_O) {
- offset = ntohs(*(__be16 *)ptr);
- ptr += 2 + offset;
+ if (!pskb_may_pull(skb, offset + 2))
+ goto discard;
+ offset += 2 + ntohs(*(__be16 *)(skb->data + offset));
}
} else
- ptr += session->offset;
+ offset += session->offset;
- offset = ptr - optr;
if (!pskb_may_pull(skb, offset))
goto discard;
@@ -735,10 +742,10 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
int (*payload_hook)(struct sk_buff *skb))
{
struct l2tp_session *session = NULL;
- unsigned char *ptr, *optr;
+ unsigned char *ptr;
u16 hdrflags;
u32 tunnel_id, session_id;
- int offset;
+ int hlen;
u16 version;
int length;
@@ -756,20 +763,22 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
}
/* Point to L2TP header */
- optr = ptr = skb->data;
+ ptr = skb->data;
/* Trace packet contents, if enabled */
if (tunnel->debug & L2TP_MSG_DATA) {
+ int i;
+
length = min(32u, skb->len);
if (!pskb_may_pull(skb, length))
goto error;
-
+ ptr = skb->data;
printk(KERN_DEBUG "%s: recv: ", tunnel->name);
- offset = 0;
+ i = 0;
do {
- printk(" %02X", ptr[offset]);
- } while (++offset < length);
+ printk(" %02X", ptr[i]);
+ } while (++i < length);
printk("\n");
}
@@ -797,23 +806,23 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
}
/* Skip flags */
- ptr += 2;
+ hlen = 2;
if (tunnel->version == L2TP_HDR_VER_2) {
/* If length is present, skip it */
if (hdrflags & L2TP_HDRFLAG_L)
- ptr += 2;
+ hlen += 2;
/* Extract tunnel and session ID */
- tunnel_id = ntohs(*(__be16 *) ptr);
- ptr += 2;
- session_id = ntohs(*(__be16 *) ptr);
- ptr += 2;
+ tunnel_id = ntohs(*(__be16 *) (ptr + hlen));
+ hlen += 2;
+ session_id = ntohs(*(__be16 *) (ptr + hlen));
+ hlen += 2;
} else {
- ptr += 2; /* skip reserved bits */
+ hlen += 2; /* skip reserved bits */
tunnel_id = tunnel->tunnel_id;
- session_id = ntohl(*(__be32 *) ptr);
- ptr += 4;
+ session_id = ntohl(*(__be32 *) (ptr + hlen));
+ hlen += 4;
}
/* Find the session context */
@@ -826,7 +835,7 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
goto error;
}
- l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
+ l2tp_recv_common(session, skb, hlen, hdrflags, length, payload_hook);
return 0;
diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index a16a48e..5341228 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -232,7 +232,7 @@ extern int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
extern struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg);
extern int l2tp_session_delete(struct l2tp_session *session);
extern void l2tp_session_free(struct l2tp_session *session);
-extern void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, unsigned char *ptr, unsigned char *optr, u16 hdrflags, int length, int (*payload_hook)(struct sk_buff *skb));
+extern void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, int offset, u16 hdrflags, int length, int (*payload_hook)(struct sk_buff *skb));
extern int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
extern int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len);
diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index d21e7eb..9046865 100644
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -123,20 +123,15 @@ static int l2tp_ip_recv(struct sk_buff *skb)
struct sock *sk;
u32 session_id;
u32 tunnel_id;
- unsigned char *ptr, *optr;
struct l2tp_session *session;
struct l2tp_tunnel *tunnel = NULL;
- int length;
- int offset;
-
- /* Point to L2TP header */
- optr = ptr = skb->data;
+ int hlen;
if (!pskb_may_pull(skb, 4))
goto discard;
- session_id = ntohl(*((__be32 *) ptr));
- ptr += 4;
+ session_id = ntohl(*(__be32 *) skb->data);
+ hlen = 4;
/* RFC3931: L2TP/IP packets have the first 4 bytes containing
* the session_id. If it is 0, the packet is a L2TP control
@@ -158,21 +153,22 @@ static int l2tp_ip_recv(struct sk_buff *skb)
/* Trace packet contents, if enabled */
if (tunnel->debug & L2TP_MSG_DATA) {
- length = min(32u, skb->len);
+ int i, length = min(32u, skb->len);
+
if (!pskb_may_pull(skb, length))
goto discard;
printk(KERN_DEBUG "%s: ip recv: ", tunnel->name);
- offset = 0;
+ i = 0;
do {
- printk(" %02X", ptr[offset]);
- } while (++offset < length);
+ printk(" %02X", skb->data[i]);
+ } while (++i < length);
printk("\n");
}
- l2tp_recv_common(session, skb, ptr, optr, 0, skb->len, tunnel->recv_payload_hook);
+ l2tp_recv_common(session, skb, hlen, 0, skb->len, tunnel->recv_payload_hook);
return 0;
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists