================================================================== BUG: KCSAN: data-race in first_packet_length / udp_poll read to 0xffff888125dff440 of 8 bytes by task 30333 on cpu 1: skb_queue_empty include/linux/skbuff.h:1494 [inline] udp_poll+0x4f/0x110 net/ipv4/udp.c:2715 sock_poll+0xed/0x250 net/socket.c:1256 vfs_poll include/linux/poll.h:90 [inline] do_pollfd fs/select.c:859 [inline] do_poll fs/select.c:907 [inline] do_sys_poll+0x4ac/0x990 fs/select.c:1001 __do_sys_ppoll fs/select.c:1101 [inline] __se_sys_ppoll fs/select.c:1081 [inline] __x64_sys_ppoll+0x161/0x1a0 fs/select.c:1081 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x44/0xa9 write to 0xffff888125dff440 of 8 bytes by task 30330 on cpu 0: __skb_queue_splice include/linux/skbuff.h:1864 [inline] skb_queue_splice_tail_init include/linux/skbuff.h:1927 [inline] first_packet_length+0x1aa/0x2a0 net/ipv4/udp.c:1582 udp_poll+0xea/0x110 net/ipv4/udp.c:2720 sock_poll+0xed/0x250 net/socket.c:1256 vfs_poll include/linux/poll.h:90 [inline] do_pollfd fs/select.c:859 [inline] do_poll fs/select.c:907 [inline] do_sys_poll+0x4ac/0x990 fs/select.c:1001 __do_sys_ppoll fs/select.c:1101 [inline] __se_sys_ppoll fs/select.c:1081 [inline] __x64_sys_ppoll+0x161/0x1a0 fs/select.c:1081 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 30330 Comm: syz-executor.3 Not tainted 5.4.0-rc3+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ================================================================== Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 30330 Comm: syz-executor.3 Not tainted 5.4.0-rc3+ #0 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+0xf5/0x159 lib/dump_stack.c:113 panic+0x210/0x640 kernel/panic.c:221 kcsan_report.cold+0xc/0x10 kernel/kcsan/report.c:302 __kcsan_setup_watchpoint+0x32e/0x4a0 kernel/kcsan/core.c:411 __tsan_write8 kernel/kcsan/kcsan.c:36 [inline] __tsan_write8+0x32/0x40 kernel/kcsan/kcsan.c:36 __skb_queue_splice include/linux/skbuff.h:1864 [inline] skb_queue_splice_tail_init include/linux/skbuff.h:1927 [inline] first_packet_length+0x1aa/0x2a0 net/ipv4/udp.c:1582 udp_poll+0xea/0x110 net/ipv4/udp.c:2720 sock_poll+0xed/0x250 net/socket.c:1256 vfs_poll include/linux/poll.h:90 [inline] do_pollfd fs/select.c:859 [inline] do_poll fs/select.c:907 [inline] do_sys_poll+0x4ac/0x990 fs/select.c:1001 __do_sys_ppoll fs/select.c:1101 [inline] __se_sys_ppoll fs/select.c:1081 [inline] __x64_sys_ppoll+0x161/0x1a0 fs/select.c:1081 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x459ef9 Code: ad b6 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f651a191c78 EFLAGS: 00000246 ORIG_RAX: 000000000000010f RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459ef9 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000020000040 RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f651a1926d4 R13: 00000000004c719a R14: 00000000004dca68 R15: 00000000ffffffff Kernel Offset: disabled Rebooting in 86400 seconds..