3b3fd068c5
rose_send_frame() dereferences `neigh->dev` when called from
rose_transmit_clear_request(), and the first occurrence of the
`neigh` is in rose_loopback_timer() as `rose_loopback_neigh`,
and it is initialized in rose_add_loopback_neigh() as NULL.
i.e when `rose_loopback_neigh` used in rose_loopback_timer()
its `->dev` was still NULL and rose_loopback_timer() was calling
rose_rx_call_request() without checking for NULL.
- net/rose/rose_link.c
This bug seems to get triggered in this line:
rose_call = (ax25_address *)neigh->dev->dev_addr;
Fix it by adding NULL checking for `rose_loopback_neigh->dev`
in rose_loopback_timer().
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Reported-by: syzbot+a1c743815982d9496393@syzkaller.appspotmail.com
Tested-by: syzbot+a1c743815982d9496393@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=9d2a7ca8c7f2e4b682c97578dfa3f236258300b3
Signed-off-by: Anmol Karn <anmol.karan123@gmail.com>
Link: https://lore.kernel.org/r/20201119191043.28813-1-anmol.karan123@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
133 lines
2.8 KiB
C
133 lines
2.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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*
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* Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
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*/
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#include <linux/types.h>
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#include <linux/slab.h>
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#include <linux/socket.h>
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#include <linux/timer.h>
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#include <net/ax25.h>
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#include <linux/skbuff.h>
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#include <net/rose.h>
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#include <linux/init.h>
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static struct sk_buff_head loopback_queue;
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#define ROSE_LOOPBACK_LIMIT 1000
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static struct timer_list loopback_timer;
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static void rose_set_loopback_timer(void);
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static void rose_loopback_timer(struct timer_list *unused);
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void rose_loopback_init(void)
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{
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skb_queue_head_init(&loopback_queue);
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timer_setup(&loopback_timer, rose_loopback_timer, 0);
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}
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static int rose_loopback_running(void)
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{
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return timer_pending(&loopback_timer);
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}
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int rose_loopback_queue(struct sk_buff *skb, struct rose_neigh *neigh)
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{
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struct sk_buff *skbn = NULL;
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if (skb_queue_len(&loopback_queue) < ROSE_LOOPBACK_LIMIT)
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skbn = skb_clone(skb, GFP_ATOMIC);
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if (skbn) {
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consume_skb(skb);
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skb_queue_tail(&loopback_queue, skbn);
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if (!rose_loopback_running())
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rose_set_loopback_timer();
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} else {
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kfree_skb(skb);
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}
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return 1;
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}
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static void rose_set_loopback_timer(void)
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{
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mod_timer(&loopback_timer, jiffies + 10);
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}
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static void rose_loopback_timer(struct timer_list *unused)
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{
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struct sk_buff *skb;
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struct net_device *dev;
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rose_address *dest;
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struct sock *sk;
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unsigned short frametype;
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unsigned int lci_i, lci_o;
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int count;
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for (count = 0; count < ROSE_LOOPBACK_LIMIT; count++) {
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skb = skb_dequeue(&loopback_queue);
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if (!skb)
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return;
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if (skb->len < ROSE_MIN_LEN) {
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kfree_skb(skb);
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continue;
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}
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lci_i = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
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frametype = skb->data[2];
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if (frametype == ROSE_CALL_REQUEST &&
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(skb->len <= ROSE_CALL_REQ_FACILITIES_OFF ||
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skb->data[ROSE_CALL_REQ_ADDR_LEN_OFF] !=
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ROSE_CALL_REQ_ADDR_LEN_VAL)) {
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kfree_skb(skb);
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continue;
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}
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dest = (rose_address *)(skb->data + ROSE_CALL_REQ_DEST_ADDR_OFF);
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lci_o = ROSE_DEFAULT_MAXVC + 1 - lci_i;
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skb_reset_transport_header(skb);
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sk = rose_find_socket(lci_o, rose_loopback_neigh);
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if (sk) {
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if (rose_process_rx_frame(sk, skb) == 0)
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kfree_skb(skb);
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continue;
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}
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if (frametype == ROSE_CALL_REQUEST) {
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if (!rose_loopback_neigh->dev) {
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kfree_skb(skb);
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continue;
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}
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dev = rose_dev_get(dest);
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if (!dev) {
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kfree_skb(skb);
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continue;
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}
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if (rose_rx_call_request(skb, dev, rose_loopback_neigh, lci_o) == 0) {
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dev_put(dev);
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kfree_skb(skb);
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}
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} else {
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kfree_skb(skb);
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}
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}
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if (!skb_queue_empty(&loopback_queue))
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mod_timer(&loopback_timer, jiffies + 1);
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}
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void __exit rose_loopback_clear(void)
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{
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struct sk_buff *skb;
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del_timer(&loopback_timer);
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while ((skb = skb_dequeue(&loopback_queue)) != NULL) {
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skb->sk = NULL;
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kfree_skb(skb);
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}
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}
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