[syzbot] general protection fault in nldev_stat_set_doit (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    70701b83e208 tcp: Fix uninitialized access in skb frags ar..
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=1654c32ab00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a262045c4c15a9e0
dashboard link: https://syzkaller.appspot.com/bug?extid=9111d2255a9710e87562
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9111d2255a9710e87562@xxxxxxxxxxxxxxxxxxxxxxxxx

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 6744 Comm: syz-executor.0 Not tainted 5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:nla_get_u32 include/net/netlink.h:1554 [inline]
RIP: 0010:nldev_stat_set_mode_doit drivers/infiniband/core/nldev.c:1909 [inline]
RIP: 0010:nldev_stat_set_doit+0x578/0x10d0 drivers/infiniband/core/nldev.c:2040
Code: fa 4c 8b a4 24 f8 02 00 00 48 b8 00 00 00 00 00 fc ff df c7 84 24 80 00 00 00 00 00 00 00 49 8d 7c 24 04 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 02
RSP: 0018:ffffc90004acf2e8 EFLAGS: 00010247
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90002b94000
RDX: 0000000000000000 RSI: ffffffff8684c5ff RDI: 0000000000000004
RBP: ffff88807cda4000 R08: 0000000000000000 R09: ffff888023fb8027
R10: ffffffff8684c5d7 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000001 R14: ffff888041024280 R15: ffff888031ade780
FS:  00007eff9dddd700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2ef24000 CR3: 0000000036902000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 rdma_nl_rcv_msg+0x36d/0x690 drivers/infiniband/core/netlink.c:195
 rdma_nl_rcv_skb drivers/infiniband/core/netlink.c:239 [inline]
 rdma_nl_rcv+0x2ee/0x430 drivers/infiniband/core/netlink.c:259
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x86d/0xda0 net/netlink/af_netlink.c:1916
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:724
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2409
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2463
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2492
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7effa0867ae9
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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007eff9dddd188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007effa097af60 RCX: 00007effa0867ae9
RDX: 0000000000000000 RSI: 0000000020000040 RDI: 0000000000000003
RBP: 00007effa08c1f6d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc008a753f R14: 00007eff9dddd300 R15: 0000000000022000
 </TASK>
Modules linked in:
---[ end trace bacb470dc6c820de ]---
RIP: 0010:nla_get_u32 include/net/netlink.h:1554 [inline]
RIP: 0010:nldev_stat_set_mode_doit drivers/infiniband/core/nldev.c:1909 [inline]
RIP: 0010:nldev_stat_set_doit+0x578/0x10d0 drivers/infiniband/core/nldev.c:2040
Code: fa 4c 8b a4 24 f8 02 00 00 48 b8 00 00 00 00 00 fc ff df c7 84 24 80 00 00 00 00 00 00 00 49 8d 7c 24 04 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 02
RSP: 0018:ffffc90004acf2e8 EFLAGS: 00010247
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90002b94000
RDX: 0000000000000000 RSI: ffffffff8684c5ff RDI: 0000000000000004
RBP: ffff88807cda4000 R08: 0000000000000000 R09: ffff888023fb8027
R10: ffffffff8684c5d7 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000001 R14: ffff888041024280 R15: ffff888031ade780
FS:  00007eff9dddd700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2ef24000 CR3: 0000000036902000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	fa                   	cli
   1:	4c 8b a4 24 f8 02 00 	mov    0x2f8(%rsp),%r12
   8:	00
   9:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  10:	fc ff df
  13:	c7 84 24 80 00 00 00 	movl   $0x0,0x80(%rsp)
  1a:	00 00 00 00
  1e:	49 8d 7c 24 04       	lea    0x4(%r12),%rdi
  23:	48 89 fa             	mov    %rdi,%rdx
  26:	48 c1 ea 03          	shr    $0x3,%rdx
* 2a:	0f b6 14 02          	movzbl (%rdx,%rax,1),%edx <-- trapping instruction
  2e:	48 89 f8             	mov    %rdi,%rax
  31:	83 e0 07             	and    $0x7,%eax
  34:	83 c0 03             	add    $0x3,%eax
  37:	38 d0                	cmp    %dl,%al
  39:	7c 08                	jl     0x43
  3b:	84 d2                	test   %dl,%dl
  3d:	0f                   	.byte 0xf
  3e:	85 02                	test   %eax,(%rdx)


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