syzbot

bridge_slave_0: entered promiscuous mode
bridge0: port 2(bridge_slave_1) entered blocking state
bridge0: port 2(bridge_slave_1) entered disabled state
bridge_slave_1: entered allmulticast mode
==================================================================
BUG: KCSAN: data-race in data_push_tail / string

write to 0xffffffff88e447c3 of 1 bytes by task 31246 on cpu 1:
 string_nocheck lib/vsprintf.c:643 [inline]
 string+0x17d/0x210 lib/vsprintf.c:721
 vsnprintf+0x539/0x8a0 lib/vsprintf.c:2852
 vscnprintf+0x42/0x90 lib/vsprintf.c:2917
 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2216
 vprintk_store+0x583/0x860 kernel/printk/printk.c:2336
 vprintk_emit+0x1a0/0x6c0 kernel/printk/printk.c:2426
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x7f/0xb0 kernel/printk/printk.c:2475
 __ext4_msg+0x198/0x1b0 fs/ext4/super.c:985
 ext4_setup_super+0x1e0/0x570 fs/ext4/super.c:-1
 __ext4_remount fs/ext4/super.c:6666 [inline]
 ext4_reconfigure+0x1626/0x1720 fs/ext4/super.c:6791
 reconfigure_super+0x319/0x5b0 fs/super.c:1083
 vfs_cmd_reconfigure fs/fsopen.c:262 [inline]
 vfs_fsconfig_locked fs/fsopen.c:291 [inline]
 __do_sys_fsconfig fs/fsopen.c:467 [inline]
 __se_sys_fsconfig+0x7ab/0x9b0 fs/fsopen.c:344
 __x64_sys_fsconfig+0x67/0x80 fs/fsopen.c:344
 x64_sys_call+0x3af/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:432
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff88e447c0 of 8 bytes by task 31221 on cpu 0:
 data_make_reusable kernel/printk/printk_ringbuffer.c:594 [inline]
 data_push_tail+0x107/0x440 kernel/printk/printk_ringbuffer.c:679
 data_alloc+0xbd/0x2c0 kernel/printk/printk_ringbuffer.c:1054
 prb_reserve+0x86a/0xb80 kernel/printk/printk_ringbuffer.c:1669
 vprintk_store+0x552/0x860 kernel/printk/printk.c:2326
 vprintk_emit+0x1a0/0x6c0 kernel/printk/printk.c:2426
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x7f/0xb0 kernel/printk/printk.c:2475
 __netdev_printk+0x2d1/0x3e0 net/core/dev.c:12411
 netdev_info+0x9e/0xd0 net/core/dev.c:12458
 netif_set_allmulti+0x15f/0x250 net/core/dev.c:9245
 dev_set_allmulti+0xd4/0x190 net/core/dev_api.c:289
 br_add_if+0x267/0xa50 net/bridge/br_if.c:605
 br_add_slave+0x2c/0x40 net/bridge/br_device.c:375
 do_set_master+0x3c0/0x4a0 net/core/rtnetlink.c:2946
 do_setlink+0xafe/0x2430 net/core/rtnetlink.c:3159
 rtnl_changelink net/core/rtnetlink.c:3769 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3928 [inline]
 rtnl_newlink+0xe84/0x12d0 net/core/rtnetlink.c:4065
 rtnetlink_rcv_msg+0x65a/0x740 net/core/rtnetlink.c:6955
 netlink_rcv_skb+0x12f/0x230 net/netlink/af_netlink.c:2534
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6982
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x605/0x6c0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x609/0x720 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x140/0x180 net/socket.c:727
 __sys_sendto+0x1aa/0x230 net/socket.c:2180
 __do_sys_sendto net/socket.c:2187 [inline]
 __se_sys_sendto net/socket.c:2183 [inline]
 __x64_sys_sendto+0x78/0x90 net/socket.c:2183
 x64_sys_call+0x2bcb/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:45
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000100002e90 -> 0x3a2932706f6f6c28

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 31221 Comm: syz-executor Tainted: G        W           6.15.0-rc3-syzkaller-00008-ga33b5a08cbbd #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================
bridge_slave_1: entered promiscuous mode