BUG: unable to handle page fault for address: ffffffffffffffdb
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD df3d067 P4D df3d067 PUD df3f067 PMD 0 
Oops: Oops: 0002 [#1] SMP KASAN PTI
CPU: 1 UID: 0 PID: 9476 Comm: syz.2.1249 Not tainted 6.16.0-syzkaller-06588-g759dfc7d04ba-dirty #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:rcuref_put+0x172/0x210
Code: c7 c7 80 c0 91 8c be 68 00 00 00 48 c7 c2 c0 c0 91 8c e8 f1 85 40 f8 48 89 df be 04 00 00 00 e8 04 c1 c5 f8 41 be ff ff ff ff <f0> 44 0f c1 33 41 8d 76 ff bf ff ff ff ff e8 9b 9f 62 f8 41 ff ce
RSP: 0018:ffffc9000425f460 EFLAGS: 00010256
RAX: ffffffff895d1401 RBX: ffffffffffffffdb RCX: ffffffff895d153c
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffffffffffdb
RBP: ffffc9000425f4f8 R08: ffffffffffffffde R09: 1ffffffffffffffb
R10: dffffc0000000000 R11: fffffbfffffffffc R12: dffffc0000000000
R13: dffffc0000000000 R14: 00000000ffffffff R15: 1ffff9200084be8c
FS:  00007f94b44716c0(0000) GS:ffff8881a3c80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffdb CR3: 000000010d9b0000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 dst_release+0x24/0x1b0
 pptp_xmit+0x14b/0x1a90
 ppp_input+0x27c/0x9f0
 pppoe_rcv_core+0xc4/0x2b0
 __release_sock+0x24c/0x350
 release_sock+0x5f/0x1f0
 pppoe_sendmsg+0x137/0x790
 __sock_sendmsg+0x21c/0x270
 ____sys_sendmsg+0x52d/0x830
 ___sys_sendmsg+0x21f/0x2a0
 __sys_sendmmsg+0x227/0x430
 __x64_sys_sendmmsg+0xa0/0xc0
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f94b358eb69
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f94b4471038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f94b37b6160 RCX: 00007f94b358eb69
RDX: 0000000000000001 RSI: 00002000000008c0 RDI: 0000000000000009
RBP: 00007f94b3611df1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f94b37b6160 R15: 00007ffff65b1148
 </TASK>
Modules linked in:
CR2: ffffffffffffffdb
---[ end trace 0000000000000000 ]---
RIP: 0010:rcuref_put+0x172/0x210
Code: c7 c7 80 c0 91 8c be 68 00 00 00 48 c7 c2 c0 c0 91 8c e8 f1 85 40 f8 48 89 df be 04 00 00 00 e8 04 c1 c5 f8 41 be ff ff ff ff <f0> 44 0f c1 33 41 8d 76 ff bf ff ff ff ff e8 9b 9f 62 f8 41 ff ce
RSP: 0018:ffffc9000425f460 EFLAGS: 00010256
RAX: ffffffff895d1401 RBX: ffffffffffffffdb RCX: ffffffff895d153c
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffffffffffdb
RBP: ffffc9000425f4f8 R08: ffffffffffffffde R09: 1ffffffffffffffb
R10: dffffc0000000000 R11: fffffbfffffffffc R12: dffffc0000000000
R13: dffffc0000000000 R14: 00000000ffffffff R15: 1ffff9200084be8c
FS:  00007f94b44716c0(0000) GS:ffff8881a3c80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffdb CR3: 000000010d9b0000 CR4: 00000000000006f0
