syzbot

RAX: 0000000000000000 RBX: 00007f8dc43f5fa0 RCX: 00007f8dc4230849
RDX: 0000000000000000 RSI: ffffffffffffffff RDI: 0000000000000007
RBP: 00007f8dc42a3986 R08: 0000000000000000 R09: 0000000000000000
==================================================================
BUG: KCSAN: data-race in data_push_tail / symbol_string

write to 0xffffffff88bb45d0 of 1 bytes by task 7063 on cpu 1:
 string_nocheck lib/vsprintf.c:650 [inline]
 symbol_string+0x1b6/0x240 lib/vsprintf.c:1006
 pointer+0x77a/0xd20 lib/vsprintf.c:2446
 vsnprintf+0x861/0xe30 lib/vsprintf.c:2852
 vscnprintf+0x42/0x90 lib/vsprintf.c:2954
 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2216
 vprintk_store+0x589/0x870 kernel/printk/printk.c:2336
 vprintk_emit+0x15e/0x680 kernel/printk/printk.c:2408
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2447
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:86
 _printk+0x7a/0xa0 kernel/printk/printk.c:2457
 printk_stack_address arch/x86/kernel/dumpstack.c:72 [inline]
 show_trace_log_lvl+0x380/0x400 arch/x86/kernel/dumpstack.c:285
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0xf2/0x150 lib/dump_stack.c:120
 dump_stack+0x15/0x1a lib/dump_stack.c:129
 fail_dump lib/fault-inject.c:53 [inline]
 should_fail_ex+0x223/0x230 lib/fault-inject.c:154
 should_fail+0xb/0x10 lib/fault-inject.c:164
 should_fail_usercopy+0x1a/0x20 lib/fault-inject-usercopy.c:37
 _inline_copy_to_user include/linux/uaccess.h:193 [inline]
 _copy_to_user+0x20/0xa0 lib/usercopy.c:26
 copy_to_user include/linux/uaccess.h:225 [inline]
 simple_read_from_buffer+0xa0/0x110 fs/libfs.c:1128
 proc_fail_nth_read+0xf9/0x140 fs/proc/base.c:1482
 vfs_read+0x1a2/0x700 fs/read_write.c:563
 ksys_read+0xe8/0x1b0 fs/read_write.c:708
 __do_sys_read fs/read_write.c:717 [inline]
 __se_sys_read fs/read_write.c:715 [inline]
 __x64_sys_read+0x42/0x50 fs/read_write.c:715
 x64_sys_call+0x2874/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff88bb45d0 of 8 bytes by task 7047 on cpu 0:
 data_make_reusable kernel/printk/printk_ringbuffer.c:594 [inline]
 data_push_tail+0x102/0x430 kernel/printk/printk_ringbuffer.c:679
 data_alloc+0xbe/0x2c0 kernel/printk/printk_ringbuffer.c:1054
 prb_reserve+0x85e/0xb60 kernel/printk/printk_ringbuffer.c:1669
 vprintk_store+0x558/0x870 kernel/printk/printk.c:2326
 vprintk_emit+0x15e/0x680 kernel/printk/printk.c:2408
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2447
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:86
 _printk+0x7a/0xa0 kernel/printk/printk.c:2457
 __show_regs+0xbc/0x450 arch/x86/kernel/process_64.c:87
 show_trace_log_lvl+0x348/0x400 arch/x86/kernel/dumpstack.c:301
 __warn+0x141/0x350 kernel/panic.c:746
 __report_bug lib/bug.c:199 [inline]
 report_bug+0x315/0x420 lib/bug.c:219
 handle_bug+0x60/0x90 arch/x86/kernel/traps.c:285
 exc_invalid_op+0x1a/0x50 arch/x86/kernel/traps.c:309
 asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:621
 refcount_warn_saturate+0x1c6/0x230 lib/refcount.c:28
 __refcount_sub_and_test include/linux/refcount.h:275 [inline]
 __refcount_dec_and_test include/linux/refcount.h:307 [inline]
 refcount_dec_and_test include/linux/refcount.h:325 [inline]
 skb_unref include/linux/skbuff.h:1233 [inline]
 __sk_skb_reason_drop net/core/skbuff.c:1213 [inline]
 sk_skb_reason_drop+0xe9/0x290 net/core/skbuff.c:1241
 kfree_skb_reason include/linux/skbuff.h:1263 [inline]
 kfree_skb include/linux/skbuff.h:1272 [inline]
 j1939_session_destroy net/can/j1939/transport.c:282 [inline]
 __j1939_session_release net/can/j1939/transport.c:294 [inline]
 kref_put include/linux/kref.h:65 [inline]
 j1939_session_put+0x157/0x2a0 net/can/j1939/transport.c:299
 j1939_sk_queue_drop_all net/can/j1939/socket.c:144 [inline]
 j1939_sk_release+0x278/0x4f0 net/can/j1939/socket.c:642
 __sock_release net/socket.c:640 [inline]
 sock_close+0x68/0x150 net/socket.c:1408
 __fput+0x17a/0x6d0 fs/file_table.c:450
 ____fput+0x1c/0x30 fs/file_table.c:478
 task_work_run+0x13a/0x1a0 kernel/task_work.c:239
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xa8/0x120 kernel/entry/common.c:218
 do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000ffffe7a3 -> 0x00000a3062317830

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 7047 Comm: syz.5.1160 Not tainted 6.12.0-syzkaller-12113-gbcc8eda6d349 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f8dc43f5fa0 R15: 00007ffd6b015418
 </TASK>
---[ end trace 0000000000000000 ]---