…KVM vectors

Sami reports that linux panic()s when resuming from suspend to RAM. This
is because when CPUs are brought back online, they re-enable any
necessary mitigations.

The Spectre-v2 and Spectre-BHB mitigations interact as both need to
done by KVM when exiting a guest. Slots KVM can use as vectors are
allocated, and templates for the mitigation are patched into the vector.

This fails if a new slot needs to be allocated once the kernel has finished
booting as it is no-longer possible to modify KVM's vectors:
| root@adam:/sys/devices/system/cpu/cpu1# echo 1 > online
| Unable to handle kernel write to read-only memory at virtual add>
| Mem abort info:
|   ESR = 0x9600004e
|   Exception class = DABT (current EL), IL = 32 bits
|   SET = 0, FnV = 0
|   EA = 0, S1PTW = 0
| Data abort info:
|   ISV = 0, ISS = 0x0000004e
|   CM = 0, WnR = 1
| swapper pgtable: 4k pages, 48-bit VAs, pgdp = 000000000f07a71c
| [ffff800000b4b800] pgd=00000009ffff8803, pud=00000009ffff7803, p>
| Internal error: Oops: 9600004e [#1] PREEMPT SMP
| Modules linked in:
| Process swapper/1 (pid: 0, stack limit = 0x0000000063153c53)
| CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.19.252-dirty #14
| Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno De>
| pstate: 000001c5 (nzcv dAIF -PAN -UAO)
| pc : __memcpy+0x48/0x180
| lr : __copy_hyp_vect_bpi+0x64/0x90

| Call trace:
|  __memcpy+0x48/0x180
|  kvm_setup_bhb_slot+0x204/0x2a8
|  spectre_bhb_enable_mitigation+0x1b8/0x1d0
|  __verify_local_cpu_caps+0x54/0xf0
|  check_local_cpu_capabilities+0xc4/0x184
|  secondary_start_kernel+0xb0/0x170
| Code: b8404423 b80044c3 36180064 f8408423 (f80084c3)
| ---[ end trace 859bcacb09555348 ]---
| Kernel panic - not syncing: Attempted to kill the idle task!
| SMP: stopping secondary CPUs
| Kernel Offset: disabled
| CPU features: 0x10,25806086
| Memory Limit: none
| ---[ end Kernel panic - not syncing: Attempted to kill the idle ]

This is only a problem on platforms where there is only one CPU that is
vulnerable to both Spectre-v2 and Spectre-BHB.

The Spectre-v2 mitigation identifies the slot it can re-use by the CPU's
'fn'. It unconditionally writes the slot number and 'template_start'
pointer. The Spectre-BHB mitigation identifies slots it can re-use by
the CPU's template_start pointer, which was previously clobbered by the
Spectre-v2 mitigation.

When there is only one CPU that is vulnerable to both issues, this causes
Spectre-v2 to try to allocate a new slot, which fails.

Change both mitigations to check whether they are changing the slot this
CPU uses before writing the percpu variables again.

This issue only exists in the stable backports for Spectre-BHB which have
to use totally different infrastructure to mainline.

Reported-by: Sami Lee <[email protected]>
Fixes: 4dd8aae ("arm64: Mitigate spectre style branch history side channels")
Signed-off-by: James Morse <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

…g the sock

[ Upstream commit 3cf7203ca620682165706f70a1b12b5194607dce ]

There is a race condition in vxlan that when deleting a vxlan device
during receiving packets, there is a possibility that the sock is
released after getting vxlan_sock vs from sk_user_data. Then in
later vxlan_ecn_decapsulate(), vxlan_get_sk_family() we will got
NULL pointer dereference. e.g.

   #0 [ffffa25ec6978a38] machine_kexec at ffffffff8c669757
   #1 [ffffa25ec6978a90] __crash_kexec at ffffffff8c7c0a4d
   #2 [ffffa25ec6978b58] crash_kexec at ffffffff8c7c1c48
   #3 [ffffa25ec6978b60] oops_end at ffffffff8c627f2b
   #4 [ffffa25ec6978b80] page_fault_oops at ffffffff8c678fcb
   #5 [ffffa25ec6978bd8] exc_page_fault at ffffffff8d109542
   #6 [ffffa25ec6978c00] asm_exc_page_fault at ffffffff8d200b62
      [exception RIP: vxlan_ecn_decapsulate+0x3b]
      RIP: ffffffffc1014e7b  RSP: ffffa25ec6978cb0  RFLAGS: 00010246
      RAX: 0000000000000008  RBX: ffff8aa000888000  RCX: 0000000000000000
      RDX: 000000000000000e  RSI: ffff8a9fc7ab803e  RDI: ffff8a9fd1168700
      RBP: ffff8a9fc7ab803e   R8: 0000000000700000   R9: 00000000000010ae
      R10: ffff8a9fcb748980  R11: 0000000000000000  R12: ffff8a9fd1168700
      R13: ffff8aa000888000  R14: 00000000002a0000  R15: 00000000000010ae
      ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
   #7 [ffffa25ec6978ce8] vxlan_rcv at ffffffffc10189cd [vxlan]
   #8 [ffffa25ec6978d90] udp_queue_rcv_one_skb at ffffffff8cfb6507
   #9 [ffffa25ec6978dc0] udp_unicast_rcv_skb at ffffffff8cfb6e45
  #10 [ffffa25ec6978dc8] __udp4_lib_rcv at ffffffff8cfb8807
  #11 [ffffa25ec6978e20] ip_protocol_deliver_rcu at ffffffff8cf76951
  #12 [ffffa25ec6978e48] ip_local_deliver at ffffffff8cf76bde
  #13 [ffffa25ec6978ea0] __netif_receive_skb_one_core at ffffffff8cecde9b
  #14 [ffffa25ec6978ec8] process_backlog at ffffffff8cece139
  #15 [ffffa25ec6978f00] __napi_poll at ffffffff8ceced1a
  #16 [ffffa25ec6978f28] net_rx_action at ffffffff8cecf1f3
  #17 [ffffa25ec6978fa0] __softirqentry_text_start at ffffffff8d4000ca
  #18 [ffffa25ec6978ff0] do_softirq at ffffffff8c6fbdc3

Reproducer: https://github.com/Mellanox/ovs-tests/blob/master/test-ovs-vxlan-remove-tunnel-during-traffic.sh

Fix this by waiting for all sk_user_data reader to finish before
releasing the sock.

Reported-by: Jianlin Shi <[email protected]>
Suggested-by: Jakub Sitnicki <[email protected]>
Fixes: 6a93cc9 ("udp-tunnel: Add a few more UDP tunnel APIs")
Signed-off-by: Hangbin Liu <[email protected]>
Reviewed-by: Jiri Pirko <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>