syzbot

 fail_dump lib/fault-inject.c:73 [inline]
 should_fail_ex+0x263/0x280 lib/fault-inject.c:174
 should_failslab+0x8c/0xb0 mm/failslab.c:46
 slab_pre_alloc_hook mm/slub.c:4522 [inline]
 slab_alloc_node mm/slub.c:4875 [inline]
 __do_kmalloc_node mm/slub.c:5294 [inline]
 __kmalloc_noprof+0xb8/0x4d0 mm/slub.c:5307
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 vc_do_resize+0x21c/0xdc0 drivers/tty/vt/vt.c:1211
==================================================================
BUG: KCSAN: data-race in data_push_tail / vsnprintf

write to 0xffffffff895a0148 of 10 bytes by task 6830 on cpu 0:
 vsnprintf+0x2ce/0x860 lib/vsprintf.c:2899
 vscnprintf+0x41/0x90 lib/vsprintf.c:3013
 printk_sprint+0x30/0x2b0 kernel/printk/printk.c:2222
 vprintk_store+0x57b/0x910 kernel/printk/printk.c:2364
 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2455
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2504
 br_set_state+0x2ae/0x3b0 net/bridge/br_stp.c:57
 br_stp_disable_port+0x5d/0x150 net/bridge/br_stp_if.c:106
 del_nbp+0xd2/0x720 net/bridge/br_if.c:343
 br_del_if+0x8e/0x100 net/bridge/br_if.c:726
 br_del_slave+0x24/0x30 net/bridge/br_device.c:382
 do_set_master+0x227/0x460 net/core/rtnetlink.c:2969
 do_setlink+0x97b/0x2940 net/core/rtnetlink.c:3187
 rtnl_group_changelink net/core/rtnetlink.c:3812 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3980 [inline]
 rtnl_newlink+0xf55/0x1400 net/core/rtnetlink.c:4108
 rtnetlink_rcv_msg+0x64b/0x720 net/core/rtnetlink.c:6994
 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2550
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:7021
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x5a8/0x680 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x5c8/0x6f0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:787 [inline]
 __sock_sendmsg net/socket.c:802 [inline]
 ____sys_sendmsg+0x563/0x5b0 net/socket.c:2698
 ___sys_sendmsg+0x195/0x1e0 net/socket.c:2752
 __sys_sendmsg net/socket.c:2784 [inline]
 __do_sys_sendmsg net/socket.c:2789 [inline]
 __se_sys_sendmsg net/socket.c:2787 [inline]
 __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2787
 x64_sys_call+0x194c/0x3020 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff895a0148 of 8 bytes by task 6832 on cpu 1:
 data_make_reusable kernel/printk/printk_ringbuffer.c:608 [inline]
 data_push_tail+0x100/0x470 kernel/printk/printk_ringbuffer.c:693
 data_alloc+0x11b/0x390 kernel/printk/printk_ringbuffer.c:1089
 prb_reserve+0x8d6/0xad0 kernel/printk/printk_ringbuffer.c:1727
 vprintk_store+0x54a/0x910 kernel/printk/printk.c:2354
 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2455
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2504
 printk_stack_address arch/x86/kernel/dumpstack.c:70 [inline]
 __show_trace_log_lvl+0x460/0x560 arch/x86/kernel/dumpstack.c:282
 __dump_stack+0x1d/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0x95/0xd0 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+0x263/0x280 lib/fault-inject.c:174
 should_failslab+0x8c/0xb0 mm/failslab.c:46
 slab_pre_alloc_hook mm/slub.c:4522 [inline]
 slab_alloc_node mm/slub.c:4875 [inline]
 __do_kmalloc_node mm/slub.c:5294 [inline]
 __kmalloc_noprof+0xb8/0x4d0 mm/slub.c:5307
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 vc_do_resize+0x21c/0xdc0 drivers/tty/vt/vt.c:1211
 __vc_resize+0x3c/0x50 drivers/tty/vt/vt.c:1331
 vt_resizex+0x356/0x3d0 drivers/tty/vt/vt_ioctl.c:711
 vt_ioctl+0x10a3/0x18d0 drivers/tty/vt/vt_ioctl.c:923
 tty_ioctl+0x7d7/0xb80 drivers/tty/tty_io.c:2792
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xce/0x140 fs/ioctl.c:583
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:583
 x64_sys_call+0x1563/0x3020 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x3fffffffffffe257 -> 0x657265746e652029

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 6832 Comm: syz.2.987 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
==================================================================
 __vc_resize+0x3c/0x50 drivers/tty/vt/vt.c:1331
 vt_resizex+0x356/0x3d0 drivers/tty/vt/vt_ioctl.c:711
 vt_ioctl+0x10a3/0x18d0 drivers/tty/vt/vt_ioctl.c:923
 tty_ioctl+0x7d7/0xb80 drivers/tty/tty_io.c:2792
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xce/0x140 fs/ioctl.c:583
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:583
 x64_sys_call+0x1563/0x3020 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f66c745c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f66c5eaf028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f66c76d5fa0 RCX: 00007f66c745c819
RDX: 0000200000000040 RSI: 000000000000560a RDI: 0000000000000003
RBP: 00007f66c5eaf090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007f66c76d6038 R14: 00007f66c76d5fa0 R15: 00007ffe72c16e28
 </TASK>