[syzbot] [net?] general protection fault in reuseport_add_sock (3)

[syzbot <syzbot+e6979a5d2f10ecb700e4@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    301927d2d2eb Merge tag 'for-net-2024-07-26' of git://git.k..
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=17332fad980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=968c4fa762577d3f
dashboard link: https://syzkaller.appspot.com/bug?extid=e6979a5d2f10ecb700e4
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11d0a623980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1538ac55980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/cb9ce2729d35/disk-301927d2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/644eaaef61a5/vmlinux-301927d2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2f92322485c3/bzImage-301927d2.xz

The issue was bisected to:

commit 6ba84574026792ce33a40c7da721dea36d0f3973
Author: Xin Long <lucien.xin@gmail.com>
Date:   Mon Nov 12 10:27:17 2018 +0000

    sctp: process sk_reuseport in sctp_get_port_local

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=14ad25bd980000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=16ad25bd980000
console output: https://syzkaller.appspot.com/x/log.txt?x=12ad25bd980000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e6979a5d2f10ecb700e4@syzkaller.appspotmail.com
Fixes: 6ba845740267 ("sctp: process sk_reuseport in sctp_get_port_local")

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 1 UID: 0 PID: 10230 Comm: syz-executor119 Not tainted 6.10.0-syzkaller-12585-g301927d2d2eb #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
RIP: 0010:reuseport_add_sock+0x27e/0x5e0 net/core/sock_reuseport.c:350
Code: 00 0f b7 5d 00 bf 01 00 00 00 89 de e8 1b a4 ff f7 83 fb 01 0f 85 a3 01 00 00 e8 6d a0 ff f7 49 8d 7e 12 48 89 f8 48 c1 e8 03 <42> 0f b6 04 28 84 c0 0f 85 4b 02 00 00 41 0f b7 5e 12 49 8d 7e 14
RSP: 0018:ffffc9000b947c98 EFLAGS: 00010202
RAX: 0000000000000002 RBX: ffff8880252ddf98 RCX: ffff888079478000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000012
RBP: 0000000000000001 R08: ffffffff8993e18d R09: 1ffffffff1fef385
R10: dffffc0000000000 R11: fffffbfff1fef386 R12: ffff8880252ddac0
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  00007f24e45b96c0(0000) GS:ffff8880b9300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffcced5f7b8 CR3: 00000000241be000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __sctp_hash_endpoint net/sctp/input.c:762 [inline]
 sctp_hash_endpoint+0x52a/0x600 net/sctp/input.c:790
 sctp_listen_start net/sctp/socket.c:8570 [inline]
 sctp_inet_listen+0x767/0xa20 net/sctp/socket.c:8625
 __sys_listen_socket net/socket.c:1883 [inline]
 __sys_listen+0x1b7/0x230 net/socket.c:1894
 __do_sys_listen net/socket.c:1902 [inline]
 __se_sys_listen net/socket.c:1900 [inline]
 __x64_sys_listen+0x5a/0x70 net/socket.c:1900
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f24e46039b9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 91 1a 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:00007f24e45b9228 EFLAGS: 00000246 ORIG_RAX: 0000000000000032
RAX: ffffffffffffffda RBX: 00007f24e468e428 RCX: 00007f24e46039b9
RDX: 00007f24e46039b9 RSI: 0000000000000003 RDI: 0000000000000004
RBP: 00007f24e468e420 R08: 00007f24e45b96c0 R09: 00007f24e45b96c0
R10: 00007f24e45b96c0 R11: 0000000000000246 R12: 00007f24e468e42c
R13: 00007f24e465a5dc R14: 0020000000000001 R15: 00007ffcced5f7d8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:reuseport_add_sock+0x27e/0x5e0 net/core/sock_reuseport.c:350
Code: 00 0f b7 5d 00 bf 01 00 00 00 89 de e8 1b a4 ff f7 83 fb 01 0f 85 a3 01 00 00 e8 6d a0 ff f7 49 8d 7e 12 48 89 f8 48 c1 e8 03 <42> 0f b6 04 28 84 c0 0f 85 4b 02 00 00 41 0f b7 5e 12 49 8d 7e 14
RSP: 0018:ffffc9000b947c98 EFLAGS: 00010202
RAX: 0000000000000002 RBX: ffff8880252ddf98 RCX: ffff888079478000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000012
RBP: 0000000000000001 R08: ffffffff8993e18d R09: 1ffffffff1fef385
R10: dffffc0000000000 R11: fffffbfff1fef386 R12: ffff8880252ddac0
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  00007f24e45b96c0(0000) GS:ffff8880b9300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffcced5f7b8 CR3: 00000000241be000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	00 0f                	add    %cl,(%rdi)
   2:	b7 5d                	mov    $0x5d,%bh
   4:	00 bf 01 00 00 00    	add    %bh,0x1(%rdi)
   a:	89 de                	mov    %ebx,%esi
   c:	e8 1b a4 ff f7       	call   0xf7ffa42c
  11:	83 fb 01             	cmp    $0x1,%ebx
  14:	0f 85 a3 01 00 00    	jne    0x1bd
  1a:	e8 6d a0 ff f7       	call   0xf7ffa08c
  1f:	49 8d 7e 12          	lea    0x12(%r14),%rdi
  23:	48 89 f8             	mov    %rdi,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 0f b6 04 28       	movzbl (%rax,%r13,1),%eax <-- trapping instruction
  2f:	84 c0                	test   %al,%al
  31:	0f 85 4b 02 00 00    	jne    0x282
  37:	41 0f b7 5e 12       	movzwl 0x12(%r14),%ebx
  3c:	49 8d 7e 14          	lea    0x14(%r14),%rdi


---
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