Re: general protection fault in kobject_get (2)

[Greg KH]

On Tue, May 19, 2020 at 09:53:16PM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    d00f26b6 Merge git://git.kernel.org/pub/scm/linux/kernel/g..
> git tree:       net-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=1316343c100000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=26d0bd769afe1a2c
> dashboard link: https://syzkaller.appspot.com/bug?extid=407fd358a932bbf639c6
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> 
> Unfortunately, I don't have any reproducer for this crash yet.
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+407fd358a932bbf639c6@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> general protection fault, probably for non-canonical address 0xdffffc0000000013: 0000 [#1] PREEMPT SMP KASAN
> KASAN: null-ptr-deref in range [0x0000000000000098-0x000000000000009f]
> CPU: 1 PID: 16682 Comm: syz-executor.3 Not tainted 5.7.0-rc4-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:kobject_get+0x30/0x150 lib/kobject.c:640
> Code: 53 e8 d4 7e c6 fd 4d 85 e4 0f 84 a2 00 00 00 e8 c6 7e c6 fd 49 8d 7c 24 3c 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 48 89 fa 83 e2 07 38 d0 7f 08 84 c0 0f 85 e7 00 00 00
> RSP: 0018:ffffc9000772f240 EFLAGS: 00010203
> RAX: dffffc0000000000 RBX: ffffffff85acfca0 RCX: ffffc9000fc67000
> RDX: 0000000000000013 RSI: ffffffff83acadfa RDI: 000000000000009c
> RBP: 0000000000000060 R08: ffff8880a8dfa4c0 R09: ffffed100a03f403
> R10: ffff8880501fa017 R11: ffffed100a03f402 R12: 0000000000000060
> R13: ffffc9000772f3c0 R14: ffff88805d1ec4e8 R15: ffff88805d1ec580
> FS:  00007f1ebed26700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000004d88f0 CR3: 00000000a86c4000 CR4: 00000000001406e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  get_device+0x20/0x30 drivers/base/core.c:2620
>  __ib_get_client_nl_info+0x1d4/0x2a0 drivers/infiniband/core/device.c:1863
>  ib_get_client_nl_info+0x30/0x180 drivers/infiniband/core/device.c:1883
>  nldev_get_chardev+0x52b/0xa40 drivers/infiniband/core/nldev.c:1625
>  rdma_nl_rcv_msg drivers/infiniband/core/netlink.c:195 [inline]
>  rdma_nl_rcv_skb drivers/infiniband/core/netlink.c:239 [inline]
>  rdma_nl_rcv+0x586/0x900 drivers/infiniband/core/netlink.c:259
>  netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
>  netlink_unicast+0x537/0x740 net/netlink/af_netlink.c:1329
>  netlink_sendmsg+0x882/0xe10 net/netlink/af_netlink.c:1918
>  sock_sendmsg_nosec net/socket.c:652 [inline]
>  sock_sendmsg+0xcf/0x120 net/socket.c:672
>  ____sys_sendmsg+0x6e6/0x810 net/socket.c:2352
>  ___sys_sendmsg+0x100/0x170 net/socket.c:2406
>  __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439
>  do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
>  entry_SYSCALL_64_after_hwframe+0x49/0xb3
> RIP: 0033:0x45c829
> Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007f1ebed25c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 00000000004ff720 RCX: 000000000045c829
> RDX: 0000000000000000 RSI: 0000000020000200 RDI: 0000000000000003
> RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
> R13: 00000000000009ad R14: 00000000004d5f10 R15: 00007f1ebed266d4
> Modules linked in:
> ---[ end trace 239938a6c4c3c99f ]---
> RIP: 0010:kobject_get+0x30/0x150 lib/kobject.c:640
> Code: 53 e8 d4 7e c6 fd 4d 85 e4 0f 84 a2 00 00 00 e8 c6 7e c6 fd 49 8d 7c 24 3c 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 48 89 fa 83 e2 07 38 d0 7f 08 84 c0 0f 85 e7 00 00 00
> RSP: 0018:ffffc9000772f240 EFLAGS: 00010203
> RAX: dffffc0000000000 RBX: ffffffff85acfca0 RCX: ffffc9000fc67000
> RDX: 0000000000000013 RSI: ffffffff83acadfa RDI: 000000000000009c
> RBP: 0000000000000060 R08: ffff8880a8dfa4c0 R09: ffffed100a03f403
> R10: ffff8880501fa017 R11: ffffed100a03f402 R12: 0000000000000060
> R13: ffffc9000772f3c0 R14: ffff88805d1ec4e8 R15: ffff88805d1ec580
> FS:  00007f1ebed26700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000000000073fad4 CR3: 00000000a86c4000 CR4: 00000000001406e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Looks like an IB/rdma issue, poke those developers please :)