From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- net/llc/llc_input.c | 224 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 224 insertions(+) create mode 100644 net/llc/llc_input.c (limited to 'net/llc/llc_input.c') diff --git a/net/llc/llc_input.c b/net/llc/llc_input.c new file mode 100644 index 000000000..8eb3d73c3 --- /dev/null +++ b/net/llc/llc_input.c @@ -0,0 +1,224 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * llc_input.c - Minimal input path for LLC + * + * Copyright (c) 1997 by Procom Technology, Inc. + * 2001-2003 by Arnaldo Carvalho de Melo + */ +#include +#include +#include +#include +#include +#include +#include + +#if 0 +#define dprintk(args...) printk(KERN_DEBUG args) +#else +#define dprintk(args...) +#endif + +/* + * Packet handler for the station, registerable because in the minimal + * LLC core that is taking shape only the very minimal subset of LLC that + * is needed for things like IPX, Appletalk, etc will stay, with all the + * rest in the llc1 and llc2 modules. + */ +static void (*llc_station_handler)(struct sk_buff *skb); + +/* + * Packet handlers for LLC_DEST_SAP and LLC_DEST_CONN. + */ +static void (*llc_type_handlers[2])(struct llc_sap *sap, + struct sk_buff *skb); + +void llc_add_pack(int type, void (*handler)(struct llc_sap *sap, + struct sk_buff *skb)) +{ + smp_wmb(); /* ensure initialisation is complete before it's called */ + if (type == LLC_DEST_SAP || type == LLC_DEST_CONN) + llc_type_handlers[type - 1] = handler; +} + +void llc_remove_pack(int type) +{ + if (type == LLC_DEST_SAP || type == LLC_DEST_CONN) + llc_type_handlers[type - 1] = NULL; + synchronize_net(); +} + +void llc_set_station_handler(void (*handler)(struct sk_buff *skb)) +{ + /* Ensure initialisation is complete before it's called */ + if (handler) + smp_wmb(); + + llc_station_handler = handler; + + if (!handler) + synchronize_net(); +} + +/** + * llc_pdu_type - returns which LLC component must handle for PDU + * @skb: input skb + * + * This function returns which LLC component must handle this PDU. + */ +static __inline__ int llc_pdu_type(struct sk_buff *skb) +{ + int type = LLC_DEST_CONN; /* I-PDU or S-PDU type */ + struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb); + + if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) != LLC_PDU_TYPE_U) + goto out; + switch (LLC_U_PDU_CMD(pdu)) { + case LLC_1_PDU_CMD_XID: + case LLC_1_PDU_CMD_UI: + case LLC_1_PDU_CMD_TEST: + type = LLC_DEST_SAP; + break; + case LLC_2_PDU_CMD_SABME: + case LLC_2_PDU_CMD_DISC: + case LLC_2_PDU_RSP_UA: + case LLC_2_PDU_RSP_DM: + case LLC_2_PDU_RSP_FRMR: + break; + default: + type = LLC_DEST_INVALID; + break; + } +out: + return type; +} + +/** + * llc_fixup_skb - initializes skb pointers + * @skb: This argument points to incoming skb + * + * Initializes internal skb pointer to start of network layer by deriving + * length of LLC header; finds length of LLC control field in LLC header + * by looking at the two lowest-order bits of the first control field + * byte; field is either 3 or 4 bytes long. + */ +static inline int llc_fixup_skb(struct sk_buff *skb) +{ + u8 llc_len = 2; + struct llc_pdu_un *pdu; + + if (unlikely(!pskb_may_pull(skb, sizeof(*pdu)))) + return 0; + + pdu = (struct llc_pdu_un *)skb->data; + if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) == LLC_PDU_TYPE_U) + llc_len = 1; + llc_len += 2; + + if (unlikely(!pskb_may_pull(skb, llc_len))) + return 0; + + skb_pull(skb, llc_len); + skb_reset_transport_header(skb); + if (skb->protocol == htons(ETH_P_802_2)) { + __be16 pdulen; + s32 data_size; + + if (skb->mac_len < ETH_HLEN) + return 0; + + pdulen = eth_hdr(skb)->h_proto; + data_size = ntohs(pdulen) - llc_len; + + if (data_size < 0 || + !pskb_may_pull(skb, data_size)) + return 0; + if (unlikely(pskb_trim_rcsum(skb, data_size))) + return 0; + } + return 1; +} + +/** + * llc_rcv - 802.2 entry point from net lower layers + * @skb: received pdu + * @dev: device that receive pdu + * @pt: packet type + * @orig_dev: the original receive net device + * + * When the system receives a 802.2 frame this function is called. It + * checks SAP and connection of received pdu and passes frame to + * llc_{station,sap,conn}_rcv for sending to proper state machine. If + * the frame is related to a busy connection (a connection is sending + * data now), it queues this frame in the connection's backlog. + */ +int llc_rcv(struct sk_buff *skb, struct net_device *dev, + struct packet_type *pt, struct net_device *orig_dev) +{ + struct llc_sap *sap; + struct llc_pdu_sn *pdu; + int dest; + int (*rcv)(struct sk_buff *, struct net_device *, + struct packet_type *, struct net_device *); + void (*sta_handler)(struct sk_buff *skb); + void (*sap_handler)(struct llc_sap *sap, struct sk_buff *skb); + + /* + * When the interface is in promisc. mode, drop all the crap that it + * receives, do not try to analyse it. + */ + if (unlikely(skb->pkt_type == PACKET_OTHERHOST)) { + dprintk("%s: PACKET_OTHERHOST\n", __func__); + goto drop; + } + skb = skb_share_check(skb, GFP_ATOMIC); + if (unlikely(!skb)) + goto out; + if (unlikely(!llc_fixup_skb(skb))) + goto drop; + pdu = llc_pdu_sn_hdr(skb); + if (unlikely(!pdu->dsap)) /* NULL DSAP, refer to station */ + goto handle_station; + sap = llc_sap_find(pdu->dsap); + if (unlikely(!sap)) {/* unknown SAP */ + dprintk("%s: llc_sap_find(%02X) failed!\n", __func__, + pdu->dsap); + goto drop; + } + /* + * First the upper layer protocols that don't need the full + * LLC functionality + */ + rcv = rcu_dereference(sap->rcv_func); + dest = llc_pdu_type(skb); + sap_handler = dest ? READ_ONCE(llc_type_handlers[dest - 1]) : NULL; + if (unlikely(!sap_handler)) { + if (rcv) + rcv(skb, dev, pt, orig_dev); + else + kfree_skb(skb); + } else { + if (rcv) { + struct sk_buff *cskb = skb_clone(skb, GFP_ATOMIC); + if (cskb) + rcv(cskb, dev, pt, orig_dev); + } + sap_handler(sap, skb); + } + llc_sap_put(sap); +out: + return 0; +drop: + kfree_skb(skb); + goto out; +handle_station: + sta_handler = READ_ONCE(llc_station_handler); + if (!sta_handler) + goto drop; + sta_handler(skb); + goto out; +} + +EXPORT_SYMBOL(llc_add_pack); +EXPORT_SYMBOL(llc_remove_pack); +EXPORT_SYMBOL(llc_set_station_handler); -- cgit v1.3.1