ice: General protection fault in ptp_clock_index

[Frederick Lawler <fred@cloudflare.com>]

Hi,

On Linux 6.12.39, we appear to hit a race reading ethtool while the
device is removed.

We have automation to remove unused interfaces during early boot
process, and when systemd is restarting the network afterwards, we
get a page fault and get into a boot-crash-loop state. We're currently
renaming the interface to something like unused0 to circumvent the
issue.

I was able to reproduce with the following snippet:

$ watch -n0.1 /sbin/ethtool -T ext0
$ echo -n "1" | sudo tee /sys/class/net/ext0/device/remove

ice 0000:41:00.0: Removed PTP clock

...

Oops: general protection fault, probably for non-canonical address 0xae09e2b3b0c665f1: 0000 [#1] PREEMPT SMP NOPTI
Tainted: [O]=OOT_MODULE
Hardware name: Lenovo HR355M-V3-G12/HR355M_V3_HPM, BIOS HR355M_V3.G.031 02/17/2025
RIP: 0010:ptp_clock_index (drivers/ptp/ptp_clock.c:476 (discriminator 1))
Code: 38 1b 4e 00 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 0f 1f 44 00 00 <8b> 87 94 03 00 00 e9 07 1b 4e 00 66 66 2e 0f 1f 84 00 00 00 00 00
All code
========
   0:	38 1b                	cmp    %bl,(%rbx)
   2:	4e 00 66 66          	rex.WRX add %r12b,0x66(%rsi)
   6:	2e 0f 1f 84 00 00 00 	cs nopl 0x0(%rax,%rax,1)
   d:	00 00
   f:	66 90                	xchg   %ax,%ax
  11:	90                   	nop
  12:	90                   	nop
  13:	90                   	nop
  14:	90                   	nop
  15:	90                   	nop
  16:	90                   	nop
  17:	90                   	nop
  18:	90                   	nop
  19:	90                   	nop
  1a:	90                   	nop
  1b:	90                   	nop
  1c:	90                   	nop
  1d:	90                   	nop
  1e:	90                   	nop
  1f:	90                   	nop
  20:	90                   	nop
  21:	f3 0f 1e fa          	endbr64
  25:	0f 1f 44 00 00       	nopl   0x0(%rax,%rax,1)
  2a:*	8b 87 94 03 00 00    	mov    0x394(%rdi),%eax		<-- trapping instruction
  30:	e9 07 1b 4e 00       	jmp    0x4e1b3c
  35:	66 66 2e 0f 1f 84 00 	data16 cs nopw 0x0(%rax,%rax,1)
  3c:	00 00 00 00

Code starting with the faulting instruction
===========================================
   0:	8b 87 94 03 00 00    	mov    0x394(%rdi),%eax
   6:	e9 07 1b 4e 00       	jmp    0x4e1b12
   b:	66 66 2e 0f 1f 84 00 	data16 cs nopw 0x0(%rax,%rax,1)
  12:	00 00 00 00
RSP: 0018:ffffb5664f657c88 EFLAGS: 00010282
RAX: ffff9f4854c201a0 RBX: ffffb5664f657d34 RCX: ffffffffc1c6a5c0
RDX: 555485607aaada55 RSI: ffffb5664f657d34 RDI: ae09e2b3b0c6625d
RBP: ffffb5664f657df0 R08: 0000000000000000 R09: ffff9f3124c570a8
R10: ffffb5664f657cc0 R11: 0000000000000001 R12: ffffffffafab4680
R13: 00007ffc828fdbb0 R14: ffff9f3124c57000 R15: ffffb5664f657d80
FS:  00007ff5abba1340(0000) GS:ffff9f402f600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff5ac03f0c0 CR3: 0000000a8768e006 CR4: 0000000000770ef0
PKRU: 55555554
Call Trace:
<TASK>
ice_get_ts_info (drivers/net/ethernet/intel/ice/ice_ethtool.c:3776 (discriminator 1)) ice
__ethtool_get_ts_info (net/ethtool/common.c:713)
__ethtool_get_ts_info (net/ethtool/common.c:713)
dev_ethtool (net/ethtool/ioctl.c:2651 net/ethtool/ioctl.c:3312 net/ethtool/ioctl.c:3390)
? srso_alias_return_thunk (arch/x86/lib/retpoline.S:182)
? trace_call_bpf (kernel/trace/bpf_trace.c:151 (discriminator 38))
? security_file_ioctl (security/security.c:2909)
? trace_call_bpf (kernel/trace/bpf_trace.c:151 (discriminator 38))
? __x64_sys_ioctl (fs/ioctl.c:893)
? kprobe_ftrace_handler (arch/x86/kernel/kprobes/ftrace.c:45 (discriminator 1))
? srso_alias_return_thunk (arch/x86/lib/retpoline.S:182)
dev_ioctl (net/core/dev_ioctl.c:720)
sock_ioctl (net/socket.c:1242 net/socket.c:1346)
__x64_sys_ioctl (fs/ioctl.c:51 fs/ioctl.c:907 fs/ioctl.c:893 fs/ioctl.c:893)
osnoise_arch_unregister (??:?)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
RIP: 0033:0x7ff5abe13d1b
Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00
All code
========
   0:	00 48 89             	add    %cl,-0x77(%rax)
   3:	44 24 18             	rex.R and $0x18,%al
   6:	31 c0                	xor    %eax,%eax
   8:	48 8d 44 24 60       	lea    0x60(%rsp),%rax
   d:	c7 04 24 10 00 00 00 	movl   $0x10,(%rsp)
  14:	48 89 44 24 08       	mov    %rax,0x8(%rsp)
  19:	48 8d 44 24 20       	lea    0x20(%rsp),%rax
  1e:	48 89 44 24 10       	mov    %rax,0x10(%rsp)
  23:	b8 10 00 00 00       	mov    $0x10,%eax
  28:	0f 05                	syscall
  2a:*	89 c2                	mov    %eax,%edx		<-- trapping instruction
  2c:	3d 00 f0 ff ff       	cmp    $0xfffff000,%eax
  31:	77 1c                	ja     0x4f
  33:	48 8b 44 24 18       	mov    0x18(%rsp),%rax
  38:	64                   	fs
  39:	48                   	rex.W
  3a:	2b                   	.byte 0x2b
  3b:	04 25                	add    $0x25,%al
  3d:	28 00                	sub    %al,(%rax)
	...

Code starting with the faulting instruction
===========================================
   0:	89 c2                	mov    %eax,%edx
   2:	3d 00 f0 ff ff       	cmp    $0xfffff000,%eax
   7:	77 1c                	ja     0x25
   9:	48 8b 44 24 18       	mov    0x18(%rsp),%rax
   e:	64                   	fs
   f:	48                   	rex.W
  10:	2b                   	.byte 0x2b
  11:	04 25                	add    $0x25,%al
  13:	28 00                	sub    %al,(%rax)
	...
RSP: 002b:00007ffc828fdb20 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000056370e675800 RCX: 00007ff5abe13d1b
RDX: 00007ffc828fdb80 RSI: 0000000000008946 RDI: 0000000000000005
RBP: 000056370e6757e0 R08: 00007ff5abee8c60 R09: 0000000000000000
R10: 00007ff5abd2f310 R11: 0000000000000246 R12: 00007ffc828fdd80
R13: 0000000000000005 R14: 00007ffc828fdb80 R15: 00007ffc828fff1a
</TASK>