[syzbot] [wireguard?] KASAN: null-ptr-deref Write in wg_packet_send_staged_packets

[syzbot] [wireguard?] KASAN: null-ptr-deref Write in wg_packet_send_staged_packets

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    d7b3af5a77e8 Add linux-next specific files for 20230728
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=10774fa1a80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=62dd327c382e3fe
dashboard link: https://syzkaller.appspot.com/bug?extid=1ef6522091226898343f
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5efa5e68267f/disk-d7b3af5a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b1f5d3e10263/vmlinux-d7b3af5a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/57cab469d186/bzImage-d7b3af5a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1ef6522091226898343f@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
BUG: KASAN: null-ptr-deref in atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:252 [inline]
BUG: KASAN: null-ptr-deref in __refcount_add include/linux/refcount.h:193 [inline]
BUG: KASAN: null-ptr-deref in __refcount_inc include/linux/refcount.h:250 [inline]
BUG: KASAN: null-ptr-deref in refcount_inc include/linux/refcount.h:267 [inline]
BUG: KASAN: null-ptr-deref in kref_get include/linux/kref.h:45 [inline]
BUG: KASAN: null-ptr-deref in wg_peer_get drivers/net/wireguard/peer.h:76 [inline]
BUG: KASAN: null-ptr-deref in wg_packet_send_staged_packets+0xd10/0x1860 drivers/net/wireguard/send.c:385
Write of size 4 at addr 0000000000000710 by task syz-executor.2/22201

CPU: 1 PID: 22201 Comm: syz-executor.2 Not tainted 6.5.0-rc3-next-20230728-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 kasan_report+0xda/0x110 mm/kasan/report.c:588
 check_region_inline mm/kasan/generic.c:181 [inline]
 kasan_check_range+0xef/0x190 mm/kasan/generic.c:187
 instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
 atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:252 [inline]
 __refcount_add include/linux/refcount.h:193 [inline]
 __refcount_inc include/linux/refcount.h:250 [inline]
 refcount_inc include/linux/refcount.h:267 [inline]
 kref_get include/linux/kref.h:45 [inline]
 wg_peer_get drivers/net/wireguard/peer.h:76 [inline]
 wg_packet_send_staged_packets+0xd10/0x1860 drivers/net/wireguard/send.c:385
 wg_packet_send_keepalive+0x48/0x300 drivers/net/wireguard/send.c:239
 wg_expired_send_persistent_keepalive+0x5e/0x70 drivers/net/wireguard/timers.c:141
 call_timer_fn+0x1a0/0x580 kernel/time/timer.c:1700
 expire_timers kernel/time/timer.c:1751 [inline]
 __run_timers+0x764/0xb10 kernel/time/timer.c:2022
 run_timer_softirq+0x58/0xd0 kernel/time/timer.c:2035
 __do_softirq+0x218/0x965 kernel/softirq.c:553
 invoke_softirq kernel/softirq.c:427 [inline]
 __irq_exit_rcu kernel/softirq.c:632 [inline]
 irq_exit_rcu+0xb7/0x120 kernel/softirq.c:644
 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1109
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:645
RIP: 0010:write_comp_data+0x3c/0x90 kernel/kcov.c:236
Code: 01 00 00 49 89 f8 65 48 8b 14 25 40 ba 03 00 a9 00 01 ff 00 74 0e 85 f6 74 59 8b 82 04 16 00 00 85 c0 74 4f 8b 82 e0 15 00 00 <83> f8 03 75 44 48 8b 82 e8 15 00 00 8b 92 e4 15 00 00 48 8b 38 48
RSP: 0018:ffffc900038bfa80 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 1ffff92000717f51 RCX: ffffffff882281ad
RDX: ffff888020b1bb80 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffc900038bfdb0
R13: ffffc900038bfbb0 R14: ffffc900038bfb90 R15: ffffc900038bfaa8
 copy_msghdr_from_user+0xcd/0x160 net/socket.c:2430
 recvmsg_copy_msghdr net/socket.c:2681 [inline]
 ___sys_recvmsg+0xdc/0x1a0 net/socket.c:2753
 do_recvmmsg+0x2af/0x740 net/socket.c:2851
 __sys_recvmmsg net/socket.c:2930 [inline]
 __do_sys_recvmmsg net/socket.c:2953 [inline]
 __se_sys_recvmmsg net/socket.c:2946 [inline]
 __x64_sys_recvmmsg+0x235/0x290 net/socket.c:2946
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fcbf367cb29
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fcbf43d00c8 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007fcbf379c050 RCX: 00007fcbf367cb29
RDX: 0000000000010106 RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 00007fcbf36c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fcbf379c050 R15: 00007ffdfffbc408
 </TASK>
==================================================================
----------------
Code disassembly (best guess):
   0:	01 00                	add    %eax,(%rax)
   2:	00 49 89             	add    %cl,-0x77(%rcx)
   5:	f8                   	clc
   6:	65 48 8b 14 25 40 ba 	mov    %gs:0x3ba40,%rdx
   d:	03 00
   f:	a9 00 01 ff 00       	test   $0xff0100,%eax
  14:	74 0e                	je     0x24
  16:	85 f6                	test   %esi,%esi
  18:	74 59                	je     0x73
  1a:	8b 82 04 16 00 00    	mov    0x1604(%rdx),%eax
  20:	85 c0                	test   %eax,%eax
  22:	74 4f                	je     0x73
  24:	8b 82 e0 15 00 00    	mov    0x15e0(%rdx),%eax
* 2a:	83 f8 03             	cmp    $0x3,%eax <-- trapping instruction
  2d:	75 44                	jne    0x73
  2f:	48 8b 82 e8 15 00 00 	mov    0x15e8(%rdx),%rax
  36:	8b 92 e4 15 00 00    	mov    0x15e4(%rdx),%edx
  3c:	48 8b 38             	mov    (%rax),%rdi
  3f:	48                   	rex.W


---
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