syzbot


KASAN: use-after-free Read in __vxlan_dev_create

Status: auto-closed as invalid on 2021/01/24 23:00
Reported-by: syzbot+781ef4d9f9ce2867fd7c@syzkaller.appspotmail.com
First crash: 640d, last: 640d
similar bugs (1):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 KASAN: use-after-free Read in __vxlan_dev_create 1 696d 696d 0/1 auto-closed as invalid on 2020/11/30 05:13

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in __hlist_del include/linux/list.h:676 [inline]
BUG: KASAN: use-after-free in hlist_del_rcu include/linux/rculist.h:427 [inline]
BUG: KASAN: use-after-free in vxlan_fdb_destroy drivers/net/vxlan.c:787 [inline]
BUG: KASAN: use-after-free in __vxlan_dev_create+0x8dc/0x970 drivers/net/vxlan.c:3278
Read of size 8 at addr ffff8880469a9380 by task syz-executor.0/26084

CPU: 1 PID: 26084 Comm: syz-executor.0 Not tainted 4.14.198-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_load8_noabort+0x68/0x70 mm/kasan/report.c:430
 __hlist_del include/linux/list.h:676 [inline]
 hlist_del_rcu include/linux/rculist.h:427 [inline]
 vxlan_fdb_destroy drivers/net/vxlan.c:787 [inline]
 __vxlan_dev_create+0x8dc/0x970 drivers/net/vxlan.c:3278
 vxlan_newlink+0xa3/0xe0 drivers/net/vxlan.c:3499
 rtnl_newlink+0xf88/0x1830 net/core/rtnetlink.c:2728
 rtnetlink_rcv_msg+0x3be/0xb10 net/core/rtnetlink.c:4316
 netlink_rcv_skb+0x125/0x390 net/netlink/af_netlink.c:2433
 netlink_unicast_kernel net/netlink/af_netlink.c:1287 [inline]
 netlink_unicast+0x437/0x610 net/netlink/af_netlink.c:1313
 netlink_sendmsg+0x62e/0xb80 net/netlink/af_netlink.c:1878
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb5/0x100 net/socket.c:656
 sock_no_sendpage+0xe2/0x110 net/core/sock.c:2595
 kernel_sendpage net/socket.c:3407 [inline]
 sock_sendpage+0xdf/0x140 net/socket.c:871
 pipe_to_sendpage+0x226/0x2d0 fs/splice.c:451
 splice_from_pipe_feed fs/splice.c:502 [inline]
 __splice_from_pipe+0x326/0x7a0 fs/splice.c:626
 splice_from_pipe fs/splice.c:661 [inline]
 generic_splice_sendpage+0xc1/0x110 fs/splice.c:832
 do_splice_from fs/splice.c:851 [inline]
 do_splice fs/splice.c:1147 [inline]
 SYSC_splice fs/splice.c:1402 [inline]
 SyS_splice+0xd59/0x1380 fs/splice.c:1382
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45e179
RSP: 002b:00007f24b52bcc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 0000000000033ec0 RCX: 000000000045e179
RDX: 0000000000000007 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 000000000118d040 R08: 000000000004ffe2 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cff4
R13: 00007ffec34330af R14: 00007f24b52bd9c0 R15: 000000000118cff4

Allocated by task 26084:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
 kmem_cache_alloc_trace+0x131/0x3d0 mm/slab.c:3618
 kmalloc include/linux/slab.h:488 [inline]
 vxlan_fdb_alloc drivers/net/vxlan.c:645 [inline]
 vxlan_fdb_create+0x11a/0x5d0 drivers/net/vxlan.c:673
 __vxlan_dev_create+0x370/0x970 drivers/net/vxlan.c:3244
 vxlan_newlink+0xa3/0xe0 drivers/net/vxlan.c:3499
 rtnl_newlink+0xf88/0x1830 net/core/rtnetlink.c:2728
 rtnetlink_rcv_msg+0x3be/0xb10 net/core/rtnetlink.c:4316
 netlink_rcv_skb+0x125/0x390 net/netlink/af_netlink.c:2433
 netlink_unicast_kernel net/netlink/af_netlink.c:1287 [inline]
 netlink_unicast+0x437/0x610 net/netlink/af_netlink.c:1313
 netlink_sendmsg+0x62e/0xb80 net/netlink/af_netlink.c:1878
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb5/0x100 net/socket.c:656
 sock_no_sendpage+0xe2/0x110 net/core/sock.c:2595
 kernel_sendpage net/socket.c:3407 [inline]
 sock_sendpage+0xdf/0x140 net/socket.c:871
 pipe_to_sendpage+0x226/0x2d0 fs/splice.c:451
 splice_from_pipe_feed fs/splice.c:502 [inline]
 __splice_from_pipe+0x326/0x7a0 fs/splice.c:626
 splice_from_pipe fs/splice.c:661 [inline]
 generic_splice_sendpage+0xc1/0x110 fs/splice.c:832
 do_splice_from fs/splice.c:851 [inline]
 do_splice fs/splice.c:1147 [inline]
 SYSC_splice fs/splice.c:1402 [inline]
 SyS_splice+0xd59/0x1380 fs/splice.c:1382
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 6338:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xc9/0x250 mm/slab.c:3815
 __rcu_reclaim kernel/rcu/rcu.h:195 [inline]
 rcu_do_batch kernel/rcu/tree.c:2699 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2962 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2929 [inline]
 rcu_process_callbacks+0x780/0x1180 kernel/rcu/tree.c:2946
 __do_softirq+0x254/0xa1d kernel/softirq.c:288

The buggy address belongs to the object at ffff8880469a9380
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 0 bytes inside of
 96-byte region [ffff8880469a9380, ffff8880469a93e0)
The buggy address belongs to the page:
page:ffffea00011a6a40 count:1 mapcount:0 mapping:ffff8880469a9000 index:0x0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff8880469a9000 0000000000000000 0000000100000020
raw: ffffea0002555d20 ffffea00027d6ee0 ffff88812fe504c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880469a9280: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff8880469a9300: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
>ffff8880469a9380: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                   ^
 ffff8880469a9400: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff8880469a9480: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
==================================================================

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-14 2020/09/26 23:00 linux-4.14.y cbfa1702aaf6 2d5ea0cb .config log report info