ip6_append_data+0x165/0x2b0 net/ipv6/ip6_output.c:1830 udpv6_sendmsg+0x69c/0x1440 net/ipv6/udp.c:1573 inet6_sendmsg+0x5f/0x80 net/ipv6/af_inet6.c:652 ================================================================== BUG: KCSAN: data-race in data_push_tail / string write to 0xffffffff86e7976a of 1 bytes by task 16446 on cpu 0: string_nocheck lib/vsprintf.c:647 [inline] string+0x17b/0x220 lib/vsprintf.c:725 vsnprintf+0xb57/0xe80 lib/vsprintf.c:2783 vscnprintf+0x3e/0x80 lib/vsprintf.c:2889 printk_sprint kernel/printk/printk.c:2222 [inline] vprintk_store+0x5f2/0xb50 kernel/printk/printk.c:2336 vprintk_emit+0xcc/0x4e0 kernel/printk/printk.c:2382 vprintk_default+0x22/0x30 kernel/printk/printk.c:2412 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50 _printk+0x76/0x96 kernel/printk/printk.c:2422 set_capacity_and_notify+0x170/0x1d0 block/genhd.c:90 loop_set_size+0x2e/0x70 drivers/block/loop.c:237 loop_configure+0xb1b/0xc20 drivers/block/loop.c:1095 lo_ioctl+0x641/0x1290 blkdev_ioctl+0x20e/0x440 block/ioctl.c:614 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:856 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 read to 0xffffffff86e79768 of 8 bytes by task 16442 on cpu 1: data_make_reusable kernel/printk/printk_ringbuffer.c:590 [inline] data_push_tail+0x10f/0x440 kernel/printk/printk_ringbuffer.c:675 data_alloc+0xbc/0x2b0 kernel/printk/printk_ringbuffer.c:1046 prb_reserve+0x897/0xbd0 kernel/printk/printk_ringbuffer.c:1555 vprintk_store+0x51c/0xb50 kernel/printk/printk.c:2326 vprintk_emit+0xcc/0x4e0 kernel/printk/printk.c:2382 vprintk_default+0x22/0x30 kernel/printk/printk.c:2412 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50 _printk+0x76/0x96 kernel/printk/printk.c:2422 printk_stack_address arch/x86/kernel/dumpstack.c:72 [inline] show_trace_log_lvl+0x5a6/0x620 arch/x86/kernel/dumpstack.c:276 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd6/0x122 lib/dump_stack.c:106 dump_stack+0x11/0x12 lib/dump_stack.c:113 fail_dump lib/fault-inject.c:55 [inline] should_fail+0x242/0x250 lib/fault-inject.c:149 should_fail_usercopy+0x16/0x20 lib/fault-inject-usercopy.c:37 copyin lib/iov_iter.c:162 [inline] _copy_from_iter+0x12d/0x820 lib/iov_iter.c:767 copy_from_iter include/linux/uio.h:171 [inline] copy_from_iter_full include/linux/uio.h:177 [inline] udplite_getfrag+0x46/0x90 include/net/udplite.h:24 __ip6_append_data+0x1a82/0x2170 net/ipv6/ip6_output.c:1696 ip6_append_data+0x165/0x2b0 net/ipv6/ip6_output.c:1830 udpv6_sendmsg+0x69c/0x1440 net/ipv6/udp.c:1573 inet6_sendmsg+0x5f/0x80 net/ipv6/af_inet6.c:652 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg net/socket.c:734 [inline] ____sys_sendmsg+0x38f/0x500 net/socket.c:2492 ___sys_sendmsg net/socket.c:2546 [inline] __sys_sendmsg+0x197/0x230 net/socket.c:2575 __do_sys_sendmsg net/socket.c:2584 [inline] __se_sys_sendmsg net/socket.c:2582 [inline] __x64_sys_sendmsg+0x42/0x50 net/socket.c:2582 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 value changed: 0x00000000ffffe8e9 -> 0x64203a34706f6f6c Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 16442 Comm: syz-executor.1 Not tainted 5.18.0-syzkaller-13842-g952923ddc011-dirty #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ================================================================== sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg net/socket.c:734 [inline] ____sys_sendmsg+0x38f/0x500 net/socket.c:2492 ___sys_sendmsg net/socket.c:2546 [inline] __sys_sendmsg+0x197/0x230 net/socket.c:2575 __do_sys_sendmsg net/socket.c:2584 [inline] __se_sys_sendmsg net/socket.c:2582 [inline] __x64_sys_sendmsg+0x42/0x50 net/socket.c:2582 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7f679617c109 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f67958f2168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f679628ef60 RCX: 00007f679617c109 RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000004 RBP: 00007f67958f21d0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 R13: 00007ffdc8f903ff R14: 00007f67958f2300 R15: 0000000000022000 syz-executor.1 (16442) used greatest stack depth: 10016 bytes left