=====================================================
BUG: KMSAN: uninit-value in strnchr+0x90/0xd0 lib/string.c:387
 strnchr+0x90/0xd0 lib/string.c:387
 bpf_bprintf_prepare+0x1c2/0x23c0 kernel/bpf/helpers.c:829
 ____bpf_trace_printk kernel/trace/bpf_trace.c:385 [inline]
 bpf_trace_printk+0xec/0x3e0 kernel/trace/bpf_trace.c:375
 ___bpf_prog_run+0x13fe/0xe0f0 kernel/bpf/core.c:1997
 __bpf_prog_run32+0xb2/0xe0 kernel/bpf/core.c:2236
 bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline]
 __bpf_prog_run include/linux/filter.h:657 [inline]
 bpf_prog_run include/linux/filter.h:664 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline]
 bpf_trace_run5+0x16f/0x350 kernel/trace/bpf_trace.c:2423
 __bpf_trace_signal_generate+0x45/0x60 include/trace/events/signal.h:50
 trace_signal_generate include/trace/events/signal.h:50 [inline]
 __send_signal_locked+0x1157/0x1200 kernel/signal.c:1187
 send_signal_locked+0x761/0xa50 kernel/signal.c:1248
 do_send_sig_info+0x19b/0x240 kernel/signal.c:1301
 group_send_sig_info+0x10c/0x160 kernel/signal.c:1453
 bpf_send_signal_common+0x386/0x410 kernel/trace/bpf_trace.c:881
 ____bpf_send_signal_thread kernel/trace/bpf_trace.c:898 [inline]
 bpf_send_signal_thread+0x2f/0x50 kernel/trace/bpf_trace.c:896
 ___bpf_prog_run+0x13fe/0xe0f0 kernel/bpf/core.c:1997
 __bpf_prog_run32+0xb2/0xe0 kernel/bpf/core.c:2236
 bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline]
 __bpf_prog_run include/linux/filter.h:657 [inline]
 bpf_prog_run include/linux/filter.h:664 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline]
 bpf_trace_run3+0x132/0x320 kernel/trace/bpf_trace.c:2421
 __bpf_trace_ext4_allocate_inode+0x34/0x50 include/trace/events/ext4.h:218
 trace_ext4_allocate_inode+0x12e/0x1d0 include/trace/events/ext4.h:218
 __ext4_new_inode+0x7416/0x79b0 fs/ext4/ialloc.c:1351
 ext4_mkdir+0x4c8/0x1520 fs/ext4/namei.c:3013
 vfs_mkdir+0x49e/0x710 fs/namei.c:4126
 do_mkdirat+0x529/0x810 fs/namei.c:4149
 __do_sys_mkdirat fs/namei.c:4164 [inline]
 __se_sys_mkdirat fs/namei.c:4162 [inline]
 __x64_sys_mkdirat+0xc8/0x120 fs/namei.c:4162
 do_syscall_64+0xd5/0x1f0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

Local variable stack created at:
 __bpf_prog_run32+0x43/0xe0 kernel/bpf/core.c:2236
 bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline]
 __bpf_prog_run include/linux/filter.h:657 [inline]
 bpf_prog_run include/linux/filter.h:664 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline]
 bpf_trace_run5+0x16f/0x350 kernel/trace/bpf_trace.c:2423

CPU: 0 PID: 5050 Comm: syz-executor.4 Not tainted 6.9.0-rc2-syzkaller-00002-g026e680b0a08 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
=====================================================