CVE-2022-50004 (Moderate severity, published 2025-06-17)
CVSS score: 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
CWE: CWE-476
Description: In the Linux kernel, the following vulnerability has been resolved:

xfrm: policy: fix metadata dst->dev xmit null pointer dereference

When we try to transmit an skb with metadata_dst attached (i.e. dst->dev
== NULL) through xfrm interface we can hit a null pointer dereference[1]
in xfrmi_xmit2() -> xfrm_lookup_with_ifid() due to the check for a
loopback skb device when there's no policy which dereferences dst->dev
unconditionally. Not having dst->dev can be interepreted as it not being
a loopback device, so just add a check for a null dst_orig->dev.

With this fix xfrm interface's Tx error counters go up as usual.

[1] net-next calltrace captured via netconsole:
  BUG: kernel NULL pointer dereference, address: 00000000000000c0
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 0 P4D 0
  Oops: 0000 [#1] PREEMPT SMP
  CPU: 1 PID: 7231 Comm: ping Kdump: loaded Not tainted 5.19.0+ #24
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.0-1.fc36 04/01/2014
  RIP: 0010:xfrm_lookup_with_ifid+0x5eb/0xa60
  Code: 8d 74 24 38 e8 26 a4 37 00 48 89 c1 e9 12 fc ff ff 49 63 ed 41 83 fd be 0f 85 be 01 00 00 41 be ff ff ff ff 45 31 ed 48 8b 03 <f6> 80 c0 00 00 00 08 75 0f 41 80 bc 24 19 0d 00 00 01 0f 84 1e 02
  RSP: 0018:ffffb0db82c679f0 EFLAGS: 00010246
  RAX: 0000000000000000 RBX: ffffd0db7fcad430 RCX: ffffb0db82c67a10
  RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffb0db82c67a80
  RBP: ffffb0db82c67a80 R08: ffffb0db82c67a14 R09: 0000000000000000
  R10: 0000000000000000 R11: ffff8fa449667dc8 R12: ffffffff966db880
  R13: 0000000000000000 R14: 00000000ffffffff R15: 0000000000000000
  FS:  00007ff35c83f000(0000) GS:ffff8fa478480000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00000000000000c0 CR3: 000000001ebb7000 CR4: 0000000000350ee0
  Call Trace:
   <TASK>
   xfrmi_xmit+0xde/0x460
   ? tcf_bpf_act+0x13d/0x2a0
   dev_hard_start_xmit+0x72/0x1e0
   __dev_queue_xmit+0x251/0xd30
   ip_finish_output2+0x140/0x550
   ip_push_pending_frames+0x56/0x80
   raw_sendmsg+0x663/0x10a0
   ? try_charge_memcg+0x3fd/0x7a0
   ? __mod_memcg_lruvec_state+0x93/0x110
   ? sock_sendmsg+0x30/0x40
   sock_sendmsg+0x30/0x40
   __sys_sendto+0xeb/0x130
   ? handle_mm_fault+0xae/0x280
   ? do_user_addr_fault+0x1e7/0x680
   ? kvm_read_and_reset_apf_flags+0x3b/0x50
   __x64_sys_sendto+0x20/0x30
   do_syscall_64+0x34/0x80
   entry_SYSCALL_64_after_hwframe+0x46/0xb0
  RIP: 0033:0x7ff35cac1366
  Code: eb 0b 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b8 0f 1f 00 41 89 ca 64 8b 04 25 18 00 00 00 85 c0 75 11 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 72 c3 90 55 48 83 ec 30 44 89 4c 24 2c 4c 89
  RSP: 002b:00007fff738e4028 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
  RAX: ffffffffffffffda RBX: 00007fff738e57b0 RCX: 00007ff35cac1366
  RDX: 0000000000000040 RSI: 0000557164e4b450 RDI: 0000000000000003
  RBP: 0000557164e4b450 R08: 00007fff738e7a2c R09: 0000000000000010
  R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000040
  R13: 00007fff738e5770 R14: 00007fff738e4030 R15: 0000001d00000001
   </TASK>
  Modules linked in: netconsole veth br_netfilter bridge bonding virtio_net [last unloaded: netconsole]
  CR2: 00000000000000c0
Statement: This issue has been fixed in Red Hat Enterprise Linux 9.3 via RHSA-2023:6583 [1].

[1]. https://access.redhat.com/errata/RHSA-2023:6583
Mitigation: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.