loop6: detected capacity change from 0 to 2048 ================================================================== BUG: KCSAN: data-race in data_push_tail / vsnprintf write to 0xffffffff88e12ef6 of 18 bytes by task 21734 on cpu 0: vsnprintf+0x2ce/0x890 lib/vsprintf.c:2804 vscnprintf+0x41/0x90 lib/vsprintf.c:2917 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2216 vprintk_store+0x599/0x860 kernel/printk/printk.c:2336 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 validate_nla lib/nlattr.c:414 [inline] __nla_validate_parse+0x1227/0x1d00 lib/nlattr.c:635 __nla_parse+0x40/0x60 lib/nlattr.c:732 __nlmsg_parse include/net/netlink.h:765 [inline] nlmsg_parse_deprecated include/net/netlink.h:806 [inline] rtm_to_fib6_config+0xbd/0xa90 net/ipv6/route.c:5063 inet6_rtm_newroute+0x5d/0x1270 net/ipv6/route.c:5565 rtnetlink_rcv_msg+0x657/0x6d0 net/core/rtnetlink.c:6964 netlink_rcv_skb+0x123/0x220 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+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+0x145/0x180 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+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffffffff88e12f00 of 8 bytes by task 21731 on cpu 1: data_make_reusable kernel/printk/printk_ringbuffer.c:594 [inline] data_push_tail+0xfd/0x420 kernel/printk/printk_ringbuffer.c:679 data_alloc+0xbf/0x2b0 kernel/printk/printk_ringbuffer.c:1054 prb_reserve+0x808/0xaf0 kernel/printk/printk_ringbuffer.c:1669 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 set_capacity_and_notify+0x14c/0x1f0 block/genhd.c:93 loop_set_size+0x2e/0x70 drivers/block/loop.c:210 loop_configure+0x7ec/0x970 drivers/block/loop.c:1067 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:906 [inline] __se_sys_ioctl+0xce/0x140 fs/ioctl.c:892 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:892 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+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f value changed: 0x0000000100001172 -> 0x3132206570797420 Reported by Kernel Concurrency Sanitizer on: CPU: 1 UID: 0 PID: 21731 Comm: syz.6.6336 Tainted: G W 6.15.0-rc6-syzkaller-00346-g5723cc3450bc #0 PREEMPT(voluntary) Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025 ================================================================== EXT4-fs (loop6): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.