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![Shigeru Yoshida](/assets/img/avatar_default.png)
syzbot reported use-after-free in cfusbl_device_notify() [1]. This
causes a stack trace like below:
BUG: KASAN: use-after-free in cfusbl_device_notify+0x7c9/0x870 net/caif/caif_usb.c:138
Read of size 8 at addr ffff88807ac4e6f0 by task kworker/u4:6/1214
CPU: 0 PID: 1214 Comm: kworker/u4:6 Not tainted 5.19.0-rc3-syzkaller-00146-g92f20ff72066 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0xeb/0x467 mm/kasan/report.c:313
print_report mm/kasan/report.c:429 [inline]
kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491
cfusbl_device_notify+0x7c9/0x870 net/caif/caif_usb.c:138
notifier_call_chain+0xb5/0x200 kernel/notifier.c:87
call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1945
call_netdevice_notifiers_extack net/core/dev.c:1983 [inline]
call_netdevice_notifiers net/core/dev.c:1997 [inline]
netdev_wait_allrefs_any net/core/dev.c:10227 [inline]
netdev_run_todo+0xbc0/0x10f0 net/core/dev.c:10341
default_device_exit_batch+0x44e/0x590 net/core/dev.c:11334
ops_exit_list+0x125/0x170 net/core/net_namespace.c:167
cleanup_net+0x4ea/0xb00 net/core/net_namespace.c:594
process_one_work+0x996/0x1610 kernel/workqueue.c:2289
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302
</TASK>
When unregistering a net device, unregister_netdevice_many_notify()
sets the device's reg_state to NETREG_UNREGISTERING, calls notifiers
with NETDEV_UNREGISTER, and adds the device to the todo list.
Later on, devices in the todo list are processed by netdev_run_todo().
netdev_run_todo() waits devices' reference count become 1 while
rebdoadcasting NETDEV_UNREGISTER notification.
When cfusbl_device_notify() is called with NETDEV_UNREGISTER multiple
times, the parent device might be freed. This could cause UAF.
Processing NETDEV_UNREGISTER multiple times also causes inbalance of
reference count for the module.
This patch fixes the issue by accepting only first NETDEV_UNREGISTER
notification.
Fixes: 7ad65bf68d
("caif: Add support for CAIF over CDC NCM USB interface")
CC: sjur.brandeland@stericsson.com <sjur.brandeland@stericsson.com>
Reported-by: syzbot+b563d33852b893653a9e@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=c3bfd8e2450adab3bffe4d80821fbbced600407f [1]
Signed-off-by: Shigeru Yoshida <syoshida@redhat.com>
Link: https://lore.kernel.org/r/20230301163913.391304-1-syoshida@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
215 lines
5.4 KiB
C
215 lines
5.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* CAIF USB handler
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* Copyright (C) ST-Ericsson AB 2011
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* Author: Sjur Brendeland
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
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#include <linux/module.h>
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#include <linux/netdevice.h>
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#include <linux/slab.h>
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#include <linux/mii.h>
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#include <linux/usb.h>
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#include <linux/usb/usbnet.h>
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#include <linux/etherdevice.h>
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#include <net/netns/generic.h>
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#include <net/caif/caif_dev.h>
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#include <net/caif/caif_layer.h>
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#include <net/caif/cfpkt.h>
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#include <net/caif/cfcnfg.h>
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MODULE_LICENSE("GPL");
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#define CFUSB_PAD_DESCR_SZ 1 /* Alignment descriptor length */
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#define CFUSB_ALIGNMENT 4 /* Number of bytes to align. */
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#define CFUSB_MAX_HEADLEN (CFUSB_PAD_DESCR_SZ + CFUSB_ALIGNMENT-1)
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#define STE_USB_VID 0x04cc /* USB Product ID for ST-Ericsson */
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#define STE_USB_PID_CAIF 0x230f /* Product id for CAIF Modems */
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struct cfusbl {
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struct cflayer layer;
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u8 tx_eth_hdr[ETH_HLEN];
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};
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static bool pack_added;
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static int cfusbl_receive(struct cflayer *layr, struct cfpkt *pkt)
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{
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u8 hpad;
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/* Remove padding. */
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cfpkt_extr_head(pkt, &hpad, 1);
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cfpkt_extr_head(pkt, NULL, hpad);
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return layr->up->receive(layr->up, pkt);
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}
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static int cfusbl_transmit(struct cflayer *layr, struct cfpkt *pkt)
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{
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struct caif_payload_info *info;
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u8 hpad;
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u8 zeros[CFUSB_ALIGNMENT];
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struct sk_buff *skb;
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struct cfusbl *usbl = container_of(layr, struct cfusbl, layer);
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skb = cfpkt_tonative(pkt);
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skb_reset_network_header(skb);
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skb->protocol = htons(ETH_P_IP);
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info = cfpkt_info(pkt);
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hpad = (info->hdr_len + CFUSB_PAD_DESCR_SZ) & (CFUSB_ALIGNMENT - 1);
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if (skb_headroom(skb) < ETH_HLEN + CFUSB_PAD_DESCR_SZ + hpad) {
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pr_warn("Headroom too small\n");
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kfree_skb(skb);
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return -EIO;
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}
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memset(zeros, 0, hpad);
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cfpkt_add_head(pkt, zeros, hpad);
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cfpkt_add_head(pkt, &hpad, 1);
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cfpkt_add_head(pkt, usbl->tx_eth_hdr, sizeof(usbl->tx_eth_hdr));
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return layr->dn->transmit(layr->dn, pkt);
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}
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static void cfusbl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
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int phyid)
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{
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if (layr->up && layr->up->ctrlcmd)
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layr->up->ctrlcmd(layr->up, ctrl, layr->id);
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}
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static struct cflayer *cfusbl_create(int phyid, const u8 ethaddr[ETH_ALEN],
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u8 braddr[ETH_ALEN])
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{
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struct cfusbl *this = kmalloc(sizeof(struct cfusbl), GFP_ATOMIC);
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if (!this)
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return NULL;
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caif_assert(offsetof(struct cfusbl, layer) == 0);
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memset(&this->layer, 0, sizeof(this->layer));
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this->layer.receive = cfusbl_receive;
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this->layer.transmit = cfusbl_transmit;
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this->layer.ctrlcmd = cfusbl_ctrlcmd;
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snprintf(this->layer.name, CAIF_LAYER_NAME_SZ, "usb%d", phyid);
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this->layer.id = phyid;
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/*
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* Construct TX ethernet header:
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* 0-5 destination address
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* 5-11 source address
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* 12-13 protocol type
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*/
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ether_addr_copy(&this->tx_eth_hdr[ETH_ALEN], braddr);
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ether_addr_copy(&this->tx_eth_hdr[ETH_ALEN], ethaddr);
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this->tx_eth_hdr[12] = cpu_to_be16(ETH_P_802_EX1) & 0xff;
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this->tx_eth_hdr[13] = (cpu_to_be16(ETH_P_802_EX1) >> 8) & 0xff;
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pr_debug("caif ethernet TX-header dst:%pM src:%pM type:%02x%02x\n",
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this->tx_eth_hdr, this->tx_eth_hdr + ETH_ALEN,
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this->tx_eth_hdr[12], this->tx_eth_hdr[13]);
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return (struct cflayer *) this;
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}
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static void cfusbl_release(struct cflayer *layer)
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{
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kfree(layer);
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}
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static struct packet_type caif_usb_type __read_mostly = {
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.type = cpu_to_be16(ETH_P_802_EX1),
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};
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static int cfusbl_device_notify(struct notifier_block *me, unsigned long what,
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void *ptr)
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{
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struct net_device *dev = netdev_notifier_info_to_dev(ptr);
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struct caif_dev_common common;
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struct cflayer *layer, *link_support;
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struct usbnet *usbnet;
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struct usb_device *usbdev;
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int res;
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if (what == NETDEV_UNREGISTER && dev->reg_state >= NETREG_UNREGISTERED)
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return 0;
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/* Check whether we have a NCM device, and find its VID/PID. */
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if (!(dev->dev.parent && dev->dev.parent->driver &&
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strcmp(dev->dev.parent->driver->name, "cdc_ncm") == 0))
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return 0;
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usbnet = netdev_priv(dev);
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usbdev = usbnet->udev;
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pr_debug("USB CDC NCM device VID:0x%4x PID:0x%4x\n",
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le16_to_cpu(usbdev->descriptor.idVendor),
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le16_to_cpu(usbdev->descriptor.idProduct));
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/* Check for VID/PID that supports CAIF */
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if (!(le16_to_cpu(usbdev->descriptor.idVendor) == STE_USB_VID &&
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le16_to_cpu(usbdev->descriptor.idProduct) == STE_USB_PID_CAIF))
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return 0;
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if (what == NETDEV_UNREGISTER)
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module_put(THIS_MODULE);
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if (what != NETDEV_REGISTER)
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return 0;
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__module_get(THIS_MODULE);
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memset(&common, 0, sizeof(common));
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common.use_frag = false;
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common.use_fcs = false;
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common.use_stx = false;
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common.link_select = CAIF_LINK_HIGH_BANDW;
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common.flowctrl = NULL;
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link_support = cfusbl_create(dev->ifindex, dev->dev_addr,
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dev->broadcast);
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if (!link_support)
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return -ENOMEM;
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if (dev->num_tx_queues > 1)
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pr_warn("USB device uses more than one tx queue\n");
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res = caif_enroll_dev(dev, &common, link_support, CFUSB_MAX_HEADLEN,
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&layer, &caif_usb_type.func);
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if (res)
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goto err;
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if (!pack_added)
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dev_add_pack(&caif_usb_type);
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pack_added = true;
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strscpy(layer->name, dev->name, sizeof(layer->name));
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return 0;
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err:
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cfusbl_release(link_support);
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return res;
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}
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static struct notifier_block caif_device_notifier = {
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.notifier_call = cfusbl_device_notify,
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.priority = 0,
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};
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static int __init cfusbl_init(void)
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{
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return register_netdevice_notifier(&caif_device_notifier);
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}
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static void __exit cfusbl_exit(void)
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{
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unregister_netdevice_notifier(&caif_device_notifier);
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dev_remove_pack(&caif_usb_type);
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}
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module_init(cfusbl_init);
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module_exit(cfusbl_exit);
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