Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fab11f6f038 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1 RAX: ffffffffffffffda RBX: 00007fab13765fa0 RCX: 00007fab1350f749 RDX: 0000200000001140 RSI: 0000000000000001 RDI: 00007fab142a3000 RBP: 00007fab11f6f090 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 ================================================================== BUG: KCSAN: data-race in data_alloc / prb_reserve write to 0xffffffff8687cb40 of 8 bytes by task 26289 on cpu 0: data_alloc+0x31c/0x390 kernel/printk/printk_ringbuffer.c:1130 prb_reserve+0x964/0xb60 kernel/printk/printk_ringbuffer.c:1724 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2302 vprintk_emit+0x15a/0x610 kernel/printk/printk.c:2402 vprintk_default+0x26/0x30 kernel/printk/printk.c:2441 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2451 batadv_hardif_activate_interface+0x21f/0x3e0 net/batman-adv/hard-interface.c:670 batadv_hard_if_event+0x2c3/0xe00 net/batman-adv/hard-interface.c:965 notifier_call_chain kernel/notifier.c:85 [inline] raw_notifier_call_chain+0x6f/0x1b0 kernel/notifier.c:453 call_netdevice_notifiers_info net/core/dev.c:2230 [inline] call_netdevice_notifiers_extack net/core/dev.c:2268 [inline] call_netdevice_notifiers net/core/dev.c:2282 [inline] __dev_notify_flags+0x1d9/0x360 net/core/dev.c:-1 netif_change_flags+0xac/0xd0 net/core/dev.c:9802 do_setlink+0x8db/0x2780 net/core/rtnetlink.c:3158 rtnl_changelink net/core/rtnetlink.c:3776 [inline] __rtnl_newlink net/core/rtnetlink.c:3935 [inline] rtnl_newlink+0xea4/0x1360 net/core/rtnetlink.c:4072 rtnetlink_rcv_msg+0x5fe/0x6d0 net/core/rtnetlink.c:6958 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2550 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6985 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x5c0/0x690 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x58b/0x6b0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg+0x145/0x180 net/socket.c:742 __sys_sendto+0x268/0x330 net/socket.c:2206 __do_sys_sendto net/socket.c:2213 [inline] __se_sys_sendto net/socket.c:2209 [inline] __x64_sys_sendto+0x76/0x90 net/socket.c:2209 x64_sys_call+0x29a7/0x3000 arch/x86/include/generated/asm/syscalls_64.h:45 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd8/0x2c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffffffff8687cb40 of 8 bytes by task 26378 on cpu 1: desc_read kernel/printk/printk_ringbuffer.c:496 [inline] desc_push_tail kernel/printk/printk_ringbuffer.c:792 [inline] desc_reserve kernel/printk/printk_ringbuffer.c:938 [inline] prb_reserve+0x249/0xb60 kernel/printk/printk_ringbuffer.c:1674 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2302 vprintk_emit+0x15a/0x610 kernel/printk/printk.c:2402 vprintk_default+0x26/0x30 kernel/printk/printk.c:2441 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2451 __show_regs+0xf0/0x440 arch/x86/kernel/process_64.c:93 show_regs_if_on_stack arch/x86/kernel/dumpstack.c:165 [inline] __show_trace_log_lvl+0x423/0x560 arch/x86/kernel/dumpstack.c:298 __dump_stack+0x1d/0x30 lib/dump_stack.c:94 dump_stack_lvl+0xe8/0x140 lib/dump_stack.c:120 dump_stack+0x15/0x1b lib/dump_stack.c:129 fail_dump lib/fault-inject.c:73 [inline] should_fail_ex+0x265/0x280 lib/fault-inject.c:174 should_failslab+0x8c/0xb0 mm/failslab.c:46 slab_pre_alloc_hook mm/slub.c:4906 [inline] slab_alloc_node mm/slub.c:5239 [inline] __do_kmalloc_node mm/slub.c:5656 [inline] __kvmalloc_node_noprof+0x149/0x6b0 mm/slub.c:7134 proc_sys_call_handler+0x248/0x4b0 fs/proc/proc_sysctl.c:583 proc_sys_read+0x1f/0x30 fs/proc/proc_sysctl.c:621 aio_read+0x1dd/0x2e0 fs/aio.c:1603 __io_submit_one fs/aio.c:-1 [inline] io_submit_one+0xb59/0x1280 fs/aio.c:2053 __do_sys_io_submit fs/aio.c:2112 [inline] __se_sys_io_submit+0xfb/0x280 fs/aio.c:2082 __x64_sys_io_submit+0x43/0x50 fs/aio.c:2082 x64_sys_call+0x2e40/0x3000 arch/x86/include/generated/asm/syscalls_64.h:210 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd8/0x2c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f value changed: 0x0000000000010918 -> 0x00000000000c61c0 Reported by Kernel Concurrency Sanitizer on: CPU: 1 UID: 0 PID: 26378 Comm: syz.5.8181 Not tainted syzkaller #0 PREEMPT(voluntary) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 ================================================================== R13: 00007fab13766038 R14: 00007fab13765fa0 R15: 00007ffc4f2371a8 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: ff c3 inc %ebx 2: 66 2e 0f 1f 84 00 00 cs nopw 0x0(%rax,%rax,1) 9: 00 00 00 c: 0f 1f 40 00 nopl 0x0(%rax) 10: 48 89 f8 mov %rdi,%rax 13: 48 89 f7 mov %rsi,%rdi 16: 48 89 d6 mov %rdx,%rsi 19: 48 89 ca mov %rcx,%rdx 1c: 4d 89 c2 mov %r8,%r10 1f: 4d 89 c8 mov %r9,%r8 22: 4c 8b 4c 24 08 mov 0x8(%rsp),%r9 27: 0f 05 syscall * 29: 48 3d 01 f0 ff ff cmp $0xfffffffffffff001,%rax <-- trapping instruction 2f: 73 01 jae 0x32 31: c3 ret 32: 48 c7 c1 a8 ff ff ff mov $0xffffffffffffffa8,%rcx 39: f7 d8 neg %eax 3b: 64 89 01 mov %eax,%fs:(%rcx) 3e: 48 rex.W