From: Dongliang Mu <mudongliangabcd@xxxxxxxxx> cdc_ncm_bind calls cdc_ncm_bind_common and sets dev->data[0] with ctx. However, in the unbind function - cdc_ncm_unbind, it calls cdc_ncm_free and frees ctx, leaving dev->data[0] as a dangling pointer. The following ioctl operation will trigger the UAF in the function cdc_ncm_set_dgram_size. Fix this by setting dev->data[0] as zero. ================================================================== BUG: KASAN: use-after-free in cdc_ncm_set_dgram_size+0xc91/0xde0 Read of size 8 at addr ffff8880755210b0 by task dhcpcd/3174 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/0x495 mm/kasan/report.c:313 print_report mm/kasan/report.c:429 [inline] kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491 cdc_ncm_set_dgram_size+0xc91/0xde0 drivers/net/usb/cdc_ncm.c:608 cdc_ncm_change_mtu+0x10c/0x140 drivers/net/usb/cdc_ncm.c:798 __dev_set_mtu net/core/dev.c:8519 [inline] dev_set_mtu_ext+0x352/0x5b0 net/core/dev.c:8572 dev_set_mtu+0x8e/0x120 net/core/dev.c:8596 dev_ifsioc+0xb87/0x1090 net/core/dev_ioctl.c:332 dev_ioctl+0x1b9/0xe30 net/core/dev_ioctl.c:586 sock_do_ioctl+0x15a/0x230 net/socket.c:1136 sock_ioctl+0x2f1/0x640 net/socket.c:1239 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f00859e70e7 RSP: 002b:00007ffedd503dd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f00858f96c8 RCX: 00007f00859e70e7 RDX: 00007ffedd513fc8 RSI: 0000000000008922 RDI: 0000000000000018 RBP: 00007ffedd524178 R08: 00007ffedd513f88 R09: 00007ffedd513f38 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffedd513fc8 R14: 0000000000000028 R15: 0000000000008922 </TASK> Allocated by task 26: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:436 [inline] ____kasan_kmalloc mm/kasan/common.c:515 [inline] ____kasan_kmalloc mm/kasan/common.c:474 [inline] __kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:524 kmalloc include/linux/slab.h:581 [inline] kzalloc include/linux/slab.h:714 [inline] cdc_ncm_bind_common+0xb8/0x2df0 drivers/net/usb/cdc_ncm.c:826 cdc_ncm_bind+0x7c/0x1c0 drivers/net/usb/cdc_ncm.c:1069 usbnet_probe+0xaf8/0x2580 drivers/net/usb/usbnet.c:1747 usb_probe_interface+0x315/0x7f0 drivers/usb/core/driver.c:396 call_driver_probe drivers/base/dd.c:541 [inline] really_probe+0x23e/0xb20 drivers/base/dd.c:620 __driver_probe_device+0x338/0x4d0 drivers/base/dd.c:751 driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:781 __device_attach_driver+0x20b/0x2f0 drivers/base/dd.c:898 bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:427 __device_attach+0x228/0x4a0 drivers/base/dd.c:969 bus_probe_device+0x1e4/0x290 drivers/base/bus.c:487 device_add+0xb83/0x1e20 drivers/base/core.c:3405 usb_set_configuration+0x101e/0x1900 drivers/usb/core/message.c:2170 usb_generic_driver_probe+0xba/0x100 drivers/usb/core/generic.c:238 usb_probe_device+0xd9/0x2c0 drivers/usb/core/driver.c:293 call_driver_probe drivers/base/dd.c:541 [inline] really_probe+0x23e/0xb20 drivers/base/dd.c:620 __driver_probe_device+0x338/0x4d0 drivers/base/dd.c:751 driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:781 __device_attach_driver+0x20b/0x2f0 drivers/base/dd.c:898 bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:427 __device_attach+0x228/0x4a0 drivers/base/dd.c:969 bus_probe_device+0x1e4/0x290 drivers/base/bus.c:487 device_add+0xb83/0x1e20 drivers/base/core.c:3405 usb_new_device.cold+0x641/0x1091 drivers/usb/core/hub.c:2566 hub_port_connect drivers/usb/core/hub.c:5363 [inline] hub_port_connect_change drivers/usb/core/hub.c:5507 [inline] port_event drivers/usb/core/hub.c:5665 [inline] hub_event+0x25c6/0x4680 drivers/usb/core/hub.c:5747 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:298 Freed by task 3742: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 kasan_set_track+0x21/0x30 mm/kasan/common.c:45 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370 ____kasan_slab_free mm/kasan/common.c:366 [inline] ____kasan_slab_free+0x166/0x1a0 mm/kasan/common.c:328 kasan_slab_free include/linux/kasan.h:200 [inline] slab_free_hook mm/slub.c:1728 [inline] slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1754 slab_free mm/slub.c:3510 [inline] kfree+0xd6/0x4d0 mm/slub.c:4552 cdc_ncm_free+0x145/0x1a0 drivers/net/usb/cdc_ncm.c:786 cdc_ncm_unbind+0x1a7/0x340 drivers/net/usb/cdc_ncm.c:1021 usbnet_disconnect+0x103/0x270 drivers/net/usb/usbnet.c:1620 usb_unbind_interface+0x1d8/0x8e0 drivers/usb/core/driver.c:458 device_remove drivers/base/dd.c:531 [inline] device_remove+0x11f/0x170 drivers/base/dd.c:523 __device_release_driver drivers/base/dd.c:1199 [inline] device_release_driver_internal+0x4a3/0x680 drivers/base/dd.c:1222 bus_remove_device+0x2eb/0x5a0 drivers/base/bus.c:529 device_del+0x4f3/0xc80 drivers/base/core.c:3592 usb_disable_device+0x35b/0x7b0 drivers/usb/core/message.c:1419 usb_disconnect.cold+0x278/0x6ec drivers/usb/core/hub.c:2228 hub_port_connect drivers/usb/core/hub.c:5207 [inline] hub_port_connect_change drivers/usb/core/hub.c:5507 [inline] port_event drivers/usb/core/hub.c:5665 [inline] hub_event+0x1e74/0x4680 drivers/usb/core/hub.c:5747 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:298 Reported-by: syzbot+eabbf2aaa999cc507108@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Dongliang Mu <mudongliangabcd@xxxxxxxxx> --- drivers/net/usb/cdc_ncm.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c index 15f91d691bba..9fc2df9f0b63 100644 --- a/drivers/net/usb/cdc_ncm.c +++ b/drivers/net/usb/cdc_ncm.c @@ -1019,6 +1019,7 @@ void cdc_ncm_unbind(struct usbnet *dev, struct usb_interface *intf) usb_set_intfdata(intf, NULL); cdc_ncm_free(ctx); + dev->data[0] = 0; } EXPORT_SYMBOL_GPL(cdc_ncm_unbind); -- 2.25.1
