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BUG: KCSAN: data-race in pfifo_fast_dequeue / pfifo_fast_enqueue

write to 0xffff888148a92dc8 of 8 bytes by task 16041 on cpu 1:
 __ptr_ring_zero_tail include/linux/ptr_ring.h:259 [inline]
 __ptr_ring_discard_one include/linux/ptr_ring.h:291 [inline]
 __ptr_ring_consume include/linux/ptr_ring.h:311 [inline]
 __skb_array_consume include/linux/skb_array.h:98 [inline]
 pfifo_fast_dequeue+0x8d1/0xf00 net/sched/sch_generic.c:770
 dequeue_skb net/sched/sch_generic.c:297 [inline]
 qdisc_restart net/sched/sch_generic.c:402 [inline]
 __qdisc_run+0x193/0xc90 net/sched/sch_generic.c:420
 __dev_xmit_skb net/core/dev.c:4184 [inline]
 __dev_queue_xmit+0xd00/0x1ee0 net/core/dev.c:4798
 dev_queue_xmit include/linux/netdevice.h:3381 [inline]
 neigh_hh_output include/net/neighbour.h:540 [inline]
 neigh_output include/net/neighbour.h:554 [inline]
 ip_finish_output2+0x77f/0x8b0 net/ipv4/ip_output.c:237
 __ip_finish_output net/ipv4/ip_output.c:-1 [inline]
 ip_finish_output+0x114/0x2a0 net/ipv4/ip_output.c:325
 NF_HOOK_COND include/linux/netfilter.h:307 [inline]
 ip_output+0xbd/0x190 net/ipv4/ip_output.c:438
 dst_output include/net/dst.h:464 [inline]
 ip_local_out+0xb9/0xe0 net/ipv4/ip_output.c:131
 iptunnel_xmit+0x3c0/0x510 net/ipv4/ip_tunnel_core.c:84
 ip_tunnel_xmit+0x1499/0x1580 net/ipv4/ip_tunnel.c:845
 __gre_xmit net/ipv4/ip_gre.c:490 [inline]
 ipgre_xmit+0x5c0/0x6a0 net/ipv4/ip_gre.c:694
 __netdev_start_xmit include/linux/netdevice.h:5273 [inline]
 netdev_start_xmit include/linux/netdevice.h:5282 [inline]
 xmit_one net/core/dev.c:3866 [inline]
 dev_hard_start_xmit+0x125/0x3e0 net/core/dev.c:3882
 __dev_queue_xmit+0xdbe/0x1ee0 net/core/dev.c:4832
 dev_queue_xmit include/linux/netdevice.h:3381 [inline]
 __bpf_tx_skb net/core/filter.c:2153 [inline]
 __bpf_redirect_no_mac net/core/filter.c:2183 [inline]
 __bpf_redirect+0x67f/0x990 net/core/filter.c:2206
 ____bpf_clone_redirect net/core/filter.c:2487 [inline]
 bpf_clone_redirect+0x20c/0x290 net/core/filter.c:2450
 bpf_prog_3e1cbbed0c4acd81+0x5f/0x68
 bpf_dispatcher_nop_func include/linux/bpf.h:1378 [inline]
 __bpf_prog_run include/linux/filter.h:723 [inline]
 bpf_prog_run include/linux/filter.h:730 [inline]
 bpf_test_run+0x284/0x610 net/bpf/test_run.c:423
 bpf_prog_test_run_skb+0x9cf/0xf50 net/bpf/test_run.c:1158
 bpf_prog_test_run+0x204/0x340 kernel/bpf/syscall.c:4703
 __sys_bpf+0x4c0/0x7c0 kernel/bpf/syscall.c:6182
 __do_sys_bpf kernel/bpf/syscall.c:6274 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6272 [inline]
 __x64_sys_bpf+0x41/0x50 kernel/bpf/syscall.c:6272
 x64_sys_call+0x28e1/0x3000 arch/x86/include/generated/asm/syscalls_64.h:322
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888148a92dc8 of 8 bytes by task 16037 on cpu 0:
 __ptr_ring_produce include/linux/ptr_ring.h:106 [inline]
 ptr_ring_produce include/linux/ptr_ring.h:129 [inline]
 skb_array_produce include/linux/skb_array.h:44 [inline]
 pfifo_fast_enqueue+0xd5/0x2c0 net/sched/sch_generic.c:741
 dev_qdisc_enqueue net/core/dev.c:4147 [inline]
 __dev_xmit_skb net/core/dev.c:4191 [inline]
 __dev_queue_xmit+0x6b5/0x1ee0 net/core/dev.c:4798
 dev_queue_xmit include/linux/netdevice.h:3381 [inline]
 __bpf_tx_skb net/core/filter.c:2153 [inline]
 __bpf_redirect_common net/core/filter.c:2197 [inline]
 __bpf_redirect+0x862/0x990 net/core/filter.c:2204
 ____bpf_clone_redirect net/core/filter.c:2487 [inline]
 bpf_clone_redirect+0x20c/0x290 net/core/filter.c:2450
 bpf_prog_8dc8bbec83c669e7+0x22/0x2a
 bpf_dispatcher_nop_func include/linux/bpf.h:1378 [inline]
 __bpf_prog_run include/linux/filter.h:723 [inline]
 bpf_prog_run include/linux/filter.h:730 [inline]
 bpf_test_run+0x284/0x610 net/bpf/test_run.c:423
 bpf_prog_test_run_skb+0x9cf/0xf50 net/bpf/test_run.c:1158
 bpf_prog_test_run+0x204/0x340 kernel/bpf/syscall.c:4703
 __sys_bpf+0x4c0/0x7c0 kernel/bpf/syscall.c:6182
 __do_sys_bpf kernel/bpf/syscall.c:6274 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6272 [inline]
 __x64_sys_bpf+0x41/0x50 kernel/bpf/syscall.c:6272
 x64_sys_call+0x28e1/0x3000 arch/x86/include/generated/asm/syscalls_64.h:322
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff888193103500 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 16037 Comm: syz.0.15211 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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