Re: [syzbot] [net?] [s390?] general protection fault in smc_diag_dump_proto

[syzbot <syzbot+f69bfae0a4eb29976e44@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
general protection fault in smc_diag_dump_proto

Oops: general protection fault, probably for non-canonical address 0xdffffc00000a2403: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: probably user-memory-access in range [0x0000000000512018-0x000000000051201f]
CPU: 0 UID: 0 PID: 6007 Comm: syz.1.56 Not tainted 6.11.0-syzkaller-05026-g39b3f4e0db5d-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
RIP: 0010:smc_diag_msg_common_fill net/smc/smc_diag.c:44 [inline]
RIP: 0010:__smc_diag_dump net/smc/smc_diag.c:89 [inline]
RIP: 0010:smc_diag_dump_proto+0x6d9/0x3270 net/smc/smc_diag.c:217
Code: 80 3c 2c 00 74 08 48 89 df e8 13 47 96 f6 48 89 5c 24 30 48 8b 1b 48 85 db 0f 84 2d 02 00 00 48 83 c3 18 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 08 48 89 df e8 e8 46 96 f6 48 8b 44 24 28 4c 8d
RSP: 0018:ffffc9000232eb00 EFLAGS: 00010206
RAX: 00000000000a2403 RBX: 0000000000512018 RCX: ffff888021765a00
RDX: 0000000000000000 RSI: 0000000080000001 RDI: 0000000000000000
RBP: ffffc9000232ef90 R08: ffffffff89984322 R09: 1ffff1100478378b
R10: dffffc0000000000 R11: ffffed100478378c R12: 1ffff1100478382b
R13: dffffc0000000000 R14: ffff888023c1bc00 R15: ffff88806a9a8010
FS:  00007f10eb3d36c0(0000) GS:ffff8880b9200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f10eb3d2fa8 CR3: 0000000029d36000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 smc_diag_dump+0x59/0xa0 net/smc/smc_diag.c:236
 netlink_dump+0x647/0xd80 net/netlink/af_netlink.c:2325
 __netlink_dump_start+0x5a2/0x790 net/netlink/af_netlink.c:2440
 netlink_dump_start include/linux/netlink.h:339 [inline]
 smc_diag_handler_dump+0x1ab/0x250 net/smc/smc_diag.c:251
 sock_diag_rcv_msg+0x3dc/0x5f0
 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2550
 netlink_unicast_kernel net/netlink/af_netlink.c:1331 [inline]
 netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1357
 netlink_sendmsg+0x8e4/0xcb0 net/netlink/af_netlink.c:1901
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:745
 sock_sendmsg+0x134/0x200 net/socket.c:768
 splice_to_socket+0xa10/0x10b0 fs/splice.c:889
 do_splice_from fs/splice.c:941 [inline]
 do_splice+0xd68/0x18e0 fs/splice.c:1354
 __do_splice fs/splice.c:1436 [inline]
 __do_sys_splice fs/splice.c:1652 [inline]
 __se_sys_splice+0x331/0x4a0 fs/splice.c:1634
 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: 0033:0x7f10ea575f19
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:00007f10eb3d3048 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007f10ea706038 RCX: 00007f10ea575f19
RDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f10ea5e4e68 R08: 0000000080000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f10ea706038 R15: 00007ffc7d1ca708
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:smc_diag_msg_common_fill net/smc/smc_diag.c:44 [inline]
RIP: 0010:__smc_diag_dump net/smc/smc_diag.c:89 [inline]
RIP: 0010:smc_diag_dump_proto+0x6d9/0x3270 net/smc/smc_diag.c:217
Code: 80 3c 2c 00 74 08 48 89 df e8 13 47 96 f6 48 89 5c 24 30 48 8b 1b 48 85 db 0f 84 2d 02 00 00 48 83 c3 18 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 08 48 89 df e8 e8 46 96 f6 48 8b 44 24 28 4c 8d
RSP: 0018:ffffc9000232eb00 EFLAGS: 00010206
RAX: 00000000000a2403 RBX: 0000000000512018 RCX: ffff888021765a00
RDX: 0000000000000000 RSI: 0000000080000001 RDI: 0000000000000000
RBP: ffffc9000232ef90 R08: ffffffff89984322 R09: 1ffff1100478378b
R10: dffffc0000000000 R11: ffffed100478378c R12: 1ffff1100478382b
R13: dffffc0000000000 R14: ffff888023c1bc00 R15: ffff88806a9a8010
FS:  00007f10eb3d36c0(0000) GS:ffff8880b9200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f10eb3d2fa8 CR3: 0000000029d36000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	80 3c 2c 00          	cmpb   $0x0,(%rsp,%rbp,1)
   4:	74 08                	je     0xe
   6:	48 89 df             	mov    %rbx,%rdi
   9:	e8 13 47 96 f6       	call   0xf6964721
   e:	48 89 5c 24 30       	mov    %rbx,0x30(%rsp)
  13:	48 8b 1b             	mov    (%rbx),%rbx
  16:	48 85 db             	test   %rbx,%rbx
  19:	0f 84 2d 02 00 00    	je     0x24c
  1f:	48 83 c3 18          	add    $0x18,%rbx
  23:	48 89 d8             	mov    %rbx,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 28 00       	cmpb   $0x0,(%rax,%r13,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	48 89 df             	mov    %rbx,%rdi
  34:	e8 e8 46 96 f6       	call   0xf6964721
  39:	48 8b 44 24 28       	mov    0x28(%rsp),%rax
  3e:	4c                   	rex.WR
  3f:	8d                   	.byte 0x8d


Tested on:

commit:         39b3f4e0 Merge tag 'hardening-v6.12-rc1' of git://git...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17a1c4a9980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5c3b301db2ae9f24
dashboard link: https://syzkaller.appspot.com/bug?extid=f69bfae0a4eb29976e44
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.