loop2: detected capacity change from 0 to 512 ================================================================== BUG: KCSAN: data-race in _prb_read_valid / prb_reserve write to 0xffffffff868dbb88 of 88 bytes by task 23987 on cpu 1: prb_reserve+0x696/0xaf0 kernel/printk/printk_ringbuffer.c:1635 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2326 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2475 br_set_state+0x28c/0x390 net/bridge/br_stp.c:57 br_init_port+0x5c/0xf0 net/bridge/br_stp_if.c:39 new_nbp+0x22b/0x300 net/bridge/br_if.c:442 br_add_if+0x1e7/0xa60 net/bridge/br_if.c:599 br_add_slave+0x2c/0x40 net/bridge/br_device.c:375 do_set_master+0x390/0x460 net/core/rtnetlink.c:2946 do_setlink+0xa43/0x2810 net/core/rtnetlink.c:3148 rtnl_changelink net/core/rtnetlink.c:3759 [inline] __rtnl_newlink net/core/rtnetlink.c:3918 [inline] rtnl_newlink+0xe75/0x12d0 net/core/rtnetlink.c:4055 rtnetlink_rcv_msg+0x5fe/0x6d0 net/core/rtnetlink.c:6944 netlink_rcv_skb+0x120/0x220 net/netlink/af_netlink.c:2534 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6971 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline] netlink_unicast+0x5a1/0x670 net/netlink/af_netlink.c:1339 netlink_sendmsg+0x58b/0x6b0 net/netlink/af_netlink.c:1883 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg+0x142/0x180 net/socket.c:727 ____sys_sendmsg+0x31e/0x4e0 net/socket.c:2566 ___sys_sendmsg+0x17b/0x1d0 net/socket.c:2620 __sys_sendmsg net/socket.c:2652 [inline] __do_sys_sendmsg net/socket.c:2657 [inline] __se_sys_sendmsg net/socket.c:2655 [inline] __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2655 x64_sys_call+0x2999/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffffffff868dbb88 of 8 bytes by task 23997 on cpu 0: desc_read kernel/printk/printk_ringbuffer.c:486 [inline] prb_first_seq kernel/printk/printk_ringbuffer.c:1957 [inline] _prb_read_valid+0x383/0x920 kernel/printk/printk_ringbuffer.c:2114 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2185 printk_get_next_message+0xc8/0x510 kernel/printk/printk.c:3005 console_emit_next_record kernel/printk/printk.c:3092 [inline] console_flush_all+0x290/0x730 kernel/printk/printk.c:3226 __console_flush_and_unlock kernel/printk/printk.c:3285 [inline] console_unlock+0xa1/0x330 kernel/printk/printk.c:3325 vprintk_emit+0x388/0x650 kernel/printk/printk.c:2450 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2475 set_capacity_and_notify+0x14c/0x1f0 block/genhd.c:93 loop_set_size+0x2e/0x70 drivers/block/loop.c:210 loop_configure+0x8d3/0xa50 drivers/block/loop.c:1068 lo_ioctl+0x559/0x15d0 drivers/block/loop.c:-1 blkdev_ioctl+0x352/0x440 block/ioctl.c:704 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xce/0x140 fs/ioctl.c:893 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:893 x64_sys_call+0x19a8/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:17 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f value changed: 0x0000000000002c17 -> 0x0000000000004c17 Reported by Kernel Concurrency Sanitizer on: CPU: 0 UID: 0 PID: 23997 Comm: syz.2.7144 Not tainted 6.16.0-rc1-syzkaller-00003-gf09079bd04a9 #0 PREEMPT(voluntary) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 ================================================================== EXT4-fs: Ignoring removed mblk_io_submit option EXT4-fs: Ignoring removed bh option EXT4-fs (loop2): encrypted files will use data=ordered instead of data journaling mode EXT4-fs (loop2): couldn't mount as ext3 due to feature incompatibilities