CVE-2023-53023

In the Linux kernel, the following vulnerability has been resolved:

net: nfc: Fix use-after-free in local_cleanup()

Fix a use-after-free that occurs in kfree_skb() called from local_cleanup(). This could happen when killing nfc daemon (e.g. neard) after detaching an nfc device. When detaching an nfc device, local_cleanup() called from nfc_llcp_unregister_device() frees local->rx_pending and decreases local->ref by kref_put() in nfc_llcp_local_put(). In the terminating process, nfc daemon releases all sockets and it leads to decreasing local->ref. After the last release of local->ref, local_cleanup() called from local_release() frees local->rx_pending again, which leads to the bug.

Setting local->rx_pending to NULL in local_cleanup() could prevent use-after-free when local_cleanup() is called twice.

Found by a modified version of syzkaller.

BUG: KASAN: use-after-free in kfree_skb()

Call Trace: dump_stack_lvl (lib/dump_stack.c:106) print_address_description.constprop.0.cold (mm/kasan/report.c:306) kasan_check_range (mm/kasan/generic.c:189) kfree_skb (net/core/skbuff.c:955) local_cleanup (net/nfc/llcp_core.c:159) nfc_llcp_local_put.part.0 (net/nfc/llcp_core.c:172) nfc_llcp_local_put (net/nfc/llcp_core.c:181) llcp_sock_destruct (net/nfc/llcp_sock.c:959) __sk_destruct (net/core/sock.c:2133) sk_destruct (net/core/sock.c:2181) __sk_free (net/core/sock.c:2192) sk_free (net/core/sock.c:2203) llcp_sock_release (net/nfc/llcp_sock.c:646) __sock_release (net/socket.c:650) sock_close (net/socket.c:1365) __fput (fs/file_table.c:306) task_work_run (kernel/task_work.c:179) ptrace_notify (kernel/signal.c:2354) syscall_exit_to_user_mode_prepare (kernel/entry/common.c:278) syscall_exit_to_user_mode (kernel/entry/common.c:296) do_syscall_64 (arch/x86/entry/common.c:86) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:106)

Allocated by task 4719: kasan_save_stack (mm/kasan/common.c:45) __kasan_slab_alloc (mm/kasan/common.c:325) slab_post_alloc_hook (mm/slab.h:766) kmem_cache_alloc_node (mm/slub.c:3497) __alloc_skb (net/core/skbuff.c:552) pn533_recv_response (drivers/nfc/pn533/usb.c:65) __usb_hcd_giveback_urb (drivers/usb/core/hcd.c:1671) usb_giveback_urb_bh (drivers/usb/core/hcd.c:1704) tasklet_action_common.isra.0 (kernel/softirq.c:797) __do_softirq (kernel/softirq.c:571)

Freed by task 1901: kasan_save_stack (mm/kasan/common.c:45) kasan_set_track (mm/kasan/common.c:52) kasan_save_free_info (mm/kasan/genericdd.c:518) __kasan_slab_free (mm/kasan/common.c:236) kmem_cache_free (mm/slub.c:3809) kfree_skbmem (net/core/skbuff.c:874) kfree_skb (net/core/skbuff.c:931) local_cleanup (net/nfc/llcp_core.c:159) nfc_llcp_unregister_device (net/nfc/llcp_core.c:1617) nfc_unregister_device (net/nfc/core.c:1179) pn53x_unregister_nfc (drivers/nfc/pn533/pn533.c:2846) pn533_usb_disconnect (drivers/nfc/pn533/usb.c:579) usb_unbind_interface (drivers/usb/core/driver.c:458) device_release_driver_internal (drivers/base/dd.c:1279) bus_remove_device (drivers/base/bus.c:529) device_del (drivers/base/core.c:3665) usb_disable_device (drivers/usb/core/message.c:1420) usb_disconnect (drivers/usb/core.c:2261) hub_event (drivers/usb/core/hub.c:5833) process_one_work (arch/x86/include/asm/jump_label.h:27 include/linux/jump_label.h:212 include/trace/events/workqueue.h:108 kernel/workqueue.c:2281) worker_thread (include/linux/list.h:282 kernel/workqueue.c:2423) kthread (kernel/kthread.c:319) ret_from_fork (arch/x86/entry/entry_64.S:301)

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/4bb4db7f3187c6e3de6b229ffc87cdb30a2d22b6
• https://git.kernel.org/stable/c/54f7be61584b8ec4c6df405f479495b9397bae4a
• https://git.kernel.org/stable/c/7f129927feaf7c10b1c38bbce630172e9a08c834
• https://git.kernel.org/stable/c/a59cdbda3714e11aa3ab579132864c4c8c6d54f9
• https://git.kernel.org/stable/c/ad1baab3a5c03692d22ce446f38596a126377f6a
• https://git.kernel.org/stable/c/b09ae26f08aaf2d85f96ea7f90ddd3387f62216f
• https://git.kernel.org/stable/c/d3605282ec3502ec8847915eb2cf1f340493ff79