KASAN: use-after-free Read in pneigh_get

Kernel	Title	Rank 🛈	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
android-49	KASAN: use-after-free Read in pneigh_get_next	19	syz			9	2189d	2222d	0/3	public: reported syz repro on 2019/06/14 20:21
upstream	KASAN: use-after-free Read in pneigh_get_next net	19	syz	done		2	2221d	2221d	12/29	fixed on 2019/07/10 21:40

8021q: adding VLAN 0 to HW filter on device batadv0 audit: type=1400 audit(1560618351.404:38): avc: denied { associate } for pid=7666 comm="syz-executor.0" name="syz0" scontext=unconfined_u:object_r:unlabeled_t:s0 tcontext=system_u:object_r:unlabeled_t:s0 tclass=filesystem permissive=1 ================================================================== BUG: KASAN: use-after-free in pneigh_get_next.isra.0+0x24b/0x280 net/core/neighbour.c:2706 Read of size 8 at addr ffff8880a4b27c00 by task syz-executor.0/8554 CPU: 1 PID: 8554 Comm: syz-executor.0 Not tainted 4.19.51 #23 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report mm/kasan/report.c:412 [inline] kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:396 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 pneigh_get_next.isra.0+0x24b/0x280 net/core/neighbour.c:2706 neigh_seq_next+0xdb/0x210 net/core/neighbour.c:2788 seq_read+0x9cf/0x1110 fs/seq_file.c:258 proc_reg_read+0x1f8/0x2b0 fs/proc/inode.c:231 do_loop_readv_writev fs/read_write.c:701 [inline] do_loop_readv_writev fs/read_write.c:688 [inline] do_iter_read+0x490/0x640 fs/read_write.c:925 vfs_readv+0xf0/0x160 fs/read_write.c:987 kernel_readv fs/splice.c:362 [inline] default_file_splice_read+0x478/0x890 fs/splice.c:417 do_splice_to+0x127/0x180 fs/splice.c:881 splice_direct_to_actor+0x256/0x890 fs/splice.c:953 do_splice_direct+0x1da/0x2a0 fs/splice.c:1062 do_sendfile+0x597/0xce0 fs/read_write.c:1447 __do_sys_sendfile64 fs/read_write.c:1508 [inline] __se_sys_sendfile64 fs/read_write.c:1494 [inline] __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1494 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4592c9 Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f3a8ac31c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00000000004592c9 RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000080000000 R11: 0000000000000246 R12: 00007f3a8ac326d4 R13: 00000000004c689d R14: 00000000004db828 R15: 00000000ffffffff Allocated by task 8555: save_stack+0x45/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc mm/kasan/kasan.c:553 [inline] kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:531 __do_kmalloc mm/slab.c:3727 [inline] __kmalloc+0x15d/0x750 mm/slab.c:3736 kmalloc include/linux/slab.h:520 [inline] pneigh_lookup+0x19c/0x460 net/core/neighbour.c:633 arp_req_set_public net/ipv4/arp.c:1014 [inline] arp_req_set+0x613/0x720 net/ipv4/arp.c:1030 arp_ioctl+0x652/0x7f0 net/ipv4/arp.c:1230 inet_ioctl+0x2a0/0x370 net/ipv4/af_inet.c:932 sock_do_ioctl+0xd8/0x2f0 net/socket.c:950 sock_ioctl+0x325/0x610 net/socket.c:1074 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:688 ksys_ioctl+0xab/0xd0 fs/ioctl.c:705 __do_sys_ioctl fs/ioctl.c:712 [inline] __se_sys_ioctl fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:710 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 8552: save_stack+0x45/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3503 [inline] kfree+0xcf/0x220 mm/slab.c:3822 pneigh_ifdown_and_unlock net/core/neighbour.c:713 [inline] neigh_ifdown+0x22f/0x2f0 net/core/neighbour.c:298 arp_ifdown+0x1d/0x21 net/ipv4/arp.c:1276 inetdev_destroy net/ipv4/devinet.c:313 [inline] inetdev_event+0xa42/0x1230 net/ipv4/devinet.c:1536 notifier_call_chain+0xc2/0x230 kernel/notifier.c:93 __raw_notifier_call_chain kernel/notifier.c:394 [inline] raw_notifier_call_chain+0x2e/0x40 kernel/notifier.c:401 call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1747 call_netdevice_notifiers net/core/dev.c:1765 [inline] rollback_registered_many+0x993/0xf90 net/core/dev.c:8005 rollback_registered+0x109/0x1d0 net/core/dev.c:8047 unregister_netdevice_queue net/core/dev.c:9094 [inline] unregister_netdevice_queue+0x1ee/0x2c0 net/core/dev.c:9087 unregister_netdevice include/linux/netdevice.h:2605 [inline] __tun_detach+0xd8a/0x1040 drivers/net/tun.c:737 tun_detach drivers/net/tun.c:754 [inline] tun_chr_close+0xe0/0x180 drivers/net/tun.c:3260 __fput+0x2dd/0x8b0 fs/file_table.c:278 ____fput+0x16/0x20 fs/file_table.c:309 task_work_run+0x145/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:193 [inline] exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:167 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x53d/0x620 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8880a4b27c00 which belongs to the cache kmalloc-64 of size 64 The buggy address is located 0 bytes inside of 64-byte region [ffff8880a4b27c00, ffff8880a4b27c40) The buggy address belongs to the page: page:ffffea000292c9c0 count:1 mapcount:0 mapping:ffff88812c3f0340 index:0x0 flags: 0x1fffc0000000100(slab) raw: 01fffc0000000100 ffffea0002613c08 ffff88812c3f1348 ffff88812c3f0340 raw: 0000000000000000 ffff8880a4b27000 0000000100000020 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880a4b27b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880a4b27b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8880a4b27c00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ^ ffff8880a4b27c80: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc ffff8880a4b27d00: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc ==================================================================