| Message ID | 20250227082642.2461118-1-edumazet@google.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 64e6a754d33d31aa844b3ee66fb93ac84ca1565e |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] llc: do not use skb_get() before dev_queue_xmit() | expand |
On Thu, Feb 27, 2025 at 08:26:42AM +0000, Eric Dumazet wrote: > syzbot is able to crash hosts [1], using llc and devices > not supporting IFF_TX_SKB_SHARING. > > In this case, e1000 driver calls eth_skb_pad(), while > the skb is shared. > > Simply replace skb_get() by skb_clone() in net/llc/llc_s_ac.c > > Note that e1000 driver might have an issue with pktgen, > because it does not clear IFF_TX_SKB_SHARING, this is an > orthogonal change. > > We need to audit other skb_get() uses in net/llc. > > [1] > > kernel BUG at net/core/skbuff.c:2178 ! > Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI > CPU: 0 UID: 0 PID: 16371 Comm: syz.2.2764 Not tainted 6.14.0-rc4-syzkaller-00052-gac9c34d1e45a #0 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 > RIP: 0010:pskb_expand_head+0x6ce/0x1240 net/core/skbuff.c:2178 > Call Trace: > <TASK> > __skb_pad+0x18a/0x610 net/core/skbuff.c:2466 > __skb_put_padto include/linux/skbuff.h:3843 [inline] > skb_put_padto include/linux/skbuff.h:3862 [inline] > eth_skb_pad include/linux/etherdevice.h:656 [inline] > e1000_xmit_frame+0x2d99/0x5800 drivers/net/ethernet/intel/e1000/e1000_main.c:3128 > __netdev_start_xmit include/linux/netdevice.h:5151 [inline] > netdev_start_xmit include/linux/netdevice.h:5160 [inline] > xmit_one net/core/dev.c:3806 [inline] > dev_hard_start_xmit+0x9a/0x7b0 net/core/dev.c:3822 > sch_direct_xmit+0x1ae/0xc30 net/sched/sch_generic.c:343 > __dev_xmit_skb net/core/dev.c:4045 [inline] > __dev_queue_xmit+0x13d4/0x43e0 net/core/dev.c:4621 > dev_queue_xmit include/linux/netdevice.h:3313 [inline] > llc_sap_action_send_test_c+0x268/0x320 net/llc/llc_s_ac.c:144 > llc_exec_sap_trans_actions net/llc/llc_sap.c:153 [inline] > llc_sap_next_state net/llc/llc_sap.c:182 [inline] > llc_sap_state_process+0x239/0x510 net/llc/llc_sap.c:209 > llc_ui_sendmsg+0xd0d/0x14e0 net/llc/af_llc.c:993 > sock_sendmsg_nosec net/socket.c:718 [inline] > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > Reported-by: syzbot+da65c993ae113742a25f@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/netdev/67c020c0.050a0220.222324.0011.GAE@google.com/T/#u > Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Simon Horman <horms@kernel.org>
Hello: This patch was applied to netdev/net.git (main) by David S. Miller <davem@davemloft.net>: On Thu, 27 Feb 2025 08:26:42 +0000 you wrote: > syzbot is able to crash hosts [1], using llc and devices > not supporting IFF_TX_SKB_SHARING. > > In this case, e1000 driver calls eth_skb_pad(), while > the skb is shared. > > Simply replace skb_get() by skb_clone() in net/llc/llc_s_ac.c > > [...] Here is the summary with links: - [net] llc: do not use skb_get() before dev_queue_xmit() https://git.kernel.org/netdev/net/c/64e6a754d33d You are awesome, thank you!
diff --git a/net/llc/llc_s_ac.c b/net/llc/llc_s_ac.c index 06fb8e6944b06aecad73739bc9337e551cf73a90..7a0cae9a8111488979ce1c22bcc7ed86ccee5269 100644 --- a/net/llc/llc_s_ac.c +++ b/net/llc/llc_s_ac.c @@ -24,7 +24,7 @@ #include <net/llc_s_ac.h> #include <net/llc_s_ev.h> #include <net/llc_sap.h> - +#include <net/sock.h> /** * llc_sap_action_unitdata_ind - forward UI PDU to network layer @@ -40,6 +40,26 @@ int llc_sap_action_unitdata_ind(struct llc_sap *sap, struct sk_buff *skb) return 0; } +static int llc_prepare_and_xmit(struct sk_buff *skb) +{ + struct llc_sap_state_ev *ev = llc_sap_ev(skb); + struct sk_buff *nskb; + int rc; + + rc = llc_mac_hdr_init(skb, ev->saddr.mac, ev->daddr.mac); + if (rc) + return rc; + + nskb = skb_clone(skb, GFP_ATOMIC); + if (!nskb) + return -ENOMEM; + + if (skb->sk) + skb_set_owner_w(nskb, skb->sk); + + return dev_queue_xmit(nskb); +} + /** * llc_sap_action_send_ui - sends UI PDU resp to UNITDATA REQ to MAC layer * @sap: SAP @@ -52,17 +72,12 @@ int llc_sap_action_unitdata_ind(struct llc_sap *sap, struct sk_buff *skb) int llc_sap_action_send_ui(struct llc_sap *sap, struct sk_buff *skb) { struct llc_sap_state_ev *ev = llc_sap_ev(skb); - int rc; llc_pdu_header_init(skb, LLC_PDU_TYPE_U, ev->saddr.lsap, ev->daddr.lsap, LLC_PDU_CMD); llc_pdu_init_as_ui_cmd(skb); - rc = llc_mac_hdr_init(skb, ev->saddr.mac, ev->daddr.mac); - if (likely(!rc)) { - skb_get(skb); - rc = dev_queue_xmit(skb); - } - return rc; + + return llc_prepare_and_xmit(skb); } /** @@ -77,17 +92,12 @@ int llc_sap_action_send_ui(struct llc_sap *sap, struct sk_buff *skb) int llc_sap_action_send_xid_c(struct llc_sap *sap, struct sk_buff *skb) { struct llc_sap_state_ev *ev = llc_sap_ev(skb); - int rc; llc_pdu_header_init(skb, LLC_PDU_TYPE_U_XID, ev->saddr.lsap, ev->daddr.lsap, LLC_PDU_CMD); llc_pdu_init_as_xid_cmd(skb, LLC_XID_NULL_CLASS_2, 0); - rc = llc_mac_hdr_init(skb, ev->saddr.mac, ev->daddr.mac); - if (likely(!rc)) { - skb_get(skb); - rc = dev_queue_xmit(skb); - } - return rc; + + return llc_prepare_and_xmit(skb); } /** @@ -133,17 +143,12 @@ int llc_sap_action_send_xid_r(struct llc_sap *sap, struct sk_buff *skb) int llc_sap_action_send_test_c(struct llc_sap *sap, struct sk_buff *skb) { struct llc_sap_state_ev *ev = llc_sap_ev(skb); - int rc; llc_pdu_header_init(skb, LLC_PDU_TYPE_U, ev->saddr.lsap, ev->daddr.lsap, LLC_PDU_CMD); llc_pdu_init_as_test_cmd(skb); - rc = llc_mac_hdr_init(skb, ev->saddr.mac, ev->daddr.mac); - if (likely(!rc)) { - skb_get(skb); - rc = dev_queue_xmit(skb); - } - return rc; + + return llc_prepare_and_xmit(skb); } int llc_sap_action_send_test_r(struct llc_sap *sap, struct sk_buff *skb)
syzbot is able to crash hosts [1], using llc and devices not supporting IFF_TX_SKB_SHARING. In this case, e1000 driver calls eth_skb_pad(), while the skb is shared. Simply replace skb_get() by skb_clone() in net/llc/llc_s_ac.c Note that e1000 driver might have an issue with pktgen, because it does not clear IFF_TX_SKB_SHARING, this is an orthogonal change. We need to audit other skb_get() uses in net/llc. [1] kernel BUG at net/core/skbuff.c:2178 ! Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI CPU: 0 UID: 0 PID: 16371 Comm: syz.2.2764 Not tainted 6.14.0-rc4-syzkaller-00052-gac9c34d1e45a #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 RIP: 0010:pskb_expand_head+0x6ce/0x1240 net/core/skbuff.c:2178 Call Trace: <TASK> __skb_pad+0x18a/0x610 net/core/skbuff.c:2466 __skb_put_padto include/linux/skbuff.h:3843 [inline] skb_put_padto include/linux/skbuff.h:3862 [inline] eth_skb_pad include/linux/etherdevice.h:656 [inline] e1000_xmit_frame+0x2d99/0x5800 drivers/net/ethernet/intel/e1000/e1000_main.c:3128 __netdev_start_xmit include/linux/netdevice.h:5151 [inline] netdev_start_xmit include/linux/netdevice.h:5160 [inline] xmit_one net/core/dev.c:3806 [inline] dev_hard_start_xmit+0x9a/0x7b0 net/core/dev.c:3822 sch_direct_xmit+0x1ae/0xc30 net/sched/sch_generic.c:343 __dev_xmit_skb net/core/dev.c:4045 [inline] __dev_queue_xmit+0x13d4/0x43e0 net/core/dev.c:4621 dev_queue_xmit include/linux/netdevice.h:3313 [inline] llc_sap_action_send_test_c+0x268/0x320 net/llc/llc_s_ac.c:144 llc_exec_sap_trans_actions net/llc/llc_sap.c:153 [inline] llc_sap_next_state net/llc/llc_sap.c:182 [inline] llc_sap_state_process+0x239/0x510 net/llc/llc_sap.c:209 llc_ui_sendmsg+0xd0d/0x14e0 net/llc/af_llc.c:993 sock_sendmsg_nosec net/socket.c:718 [inline] Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot+da65c993ae113742a25f@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/67c020c0.050a0220.222324.0011.GAE@google.com/T/#u Signed-off-by: Eric Dumazet <edumazet@google.com> --- net/llc/llc_s_ac.c | 49 +++++++++++++++++++++++++--------------------- 1 file changed, 27 insertions(+), 22 deletions(-)