=====================================================
BUG: KMSAN: uninit-value in number+0x9f8/0x2000 lib/vsprintf.c:459
CPU: 0 PID: 16374 Comm: syz-executor.4 Not tainted 5.5.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x220 lib/dump_stack.c:118
 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118
 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
 number+0x9f8/0x2000 lib/vsprintf.c:459
 vsnprintf+0x1d85/0x31b0 lib/vsprintf.c:2640
 vscnprintf+0xc2/0x180 lib/vsprintf.c:2677
 vprintk_store+0xef/0x11d0 kernel/printk/printk.c:1917
 vprintk_emit+0x2c0/0x860 kernel/printk/printk.c:1984
 vprintk_default+0x90/0xa0 kernel/printk/printk.c:2029
 vprintk_func+0x636/0x820 kernel/printk/printk_safe.c:386
 printk+0x18b/0x1d3 kernel/printk/printk.c:2062
 canfd_rcv+0x370/0x3a0 net/can/af_can.c:697
 __netif_receive_skb_one_core net/core/dev.c:5150 [inline]
 __netif_receive_skb net/core/dev.c:5264 [inline]
 netif_receive_skb_internal+0xb6e/0xc20 net/core/dev.c:5354
 netif_receive_skb+0x1d4/0x390 net/core/dev.c:5413
 tun_rx_batched include/linux/skbuff.h:4289 [inline]
 tun_get_user+0x6ad1/0x6f70 drivers/net/tun.c:1993
 tun_chr_write_iter+0x1f2/0x360 drivers/net/tun.c:2022
 call_write_iter include/linux/fs.h:1902 [inline]
 new_sync_write fs/read_write.c:483 [inline]
 __vfs_write+0xa5a/0xca0 fs/read_write.c:496
 vfs_write+0x44a/0x8f0 fs/read_write.c:558
 ksys_write+0x267/0x450 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write+0x92/0xb0 fs/read_write.c:620
 __x64_sys_write+0x4a/0x70 fs/read_write.c:620
 do_syscall_64+0xb8/0x160 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45c6c9
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fec3398ac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fec3398b6d4 RCX: 000000000045c6c9
RDX: 0000000000000004 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000cd9 R14: 00000000004cef1a R15: 000000000076bf2c

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline]
 kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:127
 kmsan_slab_alloc+0x8a/0xe0 mm/kmsan/kmsan_hooks.c:82
 slab_alloc_node mm/slub.c:2774 [inline]
 __kmalloc_node_track_caller+0xb40/0x1200 mm/slub.c:4382
 __kmalloc_reserve net/core/skbuff.c:141 [inline]
 __alloc_skb+0x2fd/0xac0 net/core/skbuff.c:209
 alloc_skb include/linux/skbuff.h:1049 [inline]
 alloc_skb_with_frags+0x18c/0xa70 net/core/skbuff.c:5664
 sock_alloc_send_pskb+0xada/0xc60 net/core/sock.c:2242
 tun_alloc_skb drivers/net/tun.c:1529 [inline]
 tun_get_user+0x10e1/0x6f70 drivers/net/tun.c:1843
 tun_chr_write_iter+0x1f2/0x360 drivers/net/tun.c:2022
 call_write_iter include/linux/fs.h:1902 [inline]
 new_sync_write fs/read_write.c:483 [inline]
 __vfs_write+0xa5a/0xca0 fs/read_write.c:496
 vfs_write+0x44a/0x8f0 fs/read_write.c:558
 ksys_write+0x267/0x450 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write+0x92/0xb0 fs/read_write.c:620
 __x64_sys_write+0x4a/0x70 fs/read_write.c:620
 do_syscall_64+0xb8/0x160 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
=====================================================