5.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit 64e6a754d33d31aa844b3ee66fb93ac84ca1565e ]
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/... Signed-off-by: Eric Dumazet edumazet@google.com Reviewed-by: Simon Horman horms@kernel.org Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/llc/llc_s_ac.c | 49 +++++++++++++++++++++++++--------------------- 1 file changed, 27 insertions(+), 22 deletions(-)
diff --git a/net/llc/llc_s_ac.c b/net/llc/llc_s_ac.c index df26557a02448..942ace4af18d8 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_unit_data_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)