Bug 2513151 (CVE-2026-68336)

Summary: CVE-2026-68336 kernel: bonding: fix devconf_all NULL dereference when IPv6 is disabled
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: low    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's bonding module. When a system is booted with IPv6 disabled, the bonding module incorrectly attempts to send IPv6 Network Service (NS) packets. This leads to a null pointer dereference, which is an attempt to access uninitialized memory. The consequence of this flaw is a kernel panic, resulting in a system crash and a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-08-10 12:22:00 UTC 
In the Linux kernel, the following vulnerability has been resolved:

bonding: fix devconf_all NULL dereference when IPv6 is disabled

When booting with the 'ipv6.disable=1' parameter, the devconf_all is
never initialized because inet6_init() exits before addrconf_init() is
called which initializes it. bond_send_validate(), however, will still
call bond_ns_send_all() even ipv6 is indeed disabled. It will lead to
NULL derefence of net->ipv6.devconf_all in ip6_pol_route().

 BUG: kernel NULL pointer dereference, address: 000000000000000c
 [...]
 Workqueue: bond0 bond_arp_monitor [bonding]
 RIP: 0010:ip6_pol_route+0x69/0x480
 [...]
 Call Trace:
  <TASK>
  ? srso_return_thunk+0x5/0x5f
  ? __pfx_ip6_pol_route_output+0x10/0x10
  fib6_rule_lookup+0xfe/0x260
  ? wakeup_preempt+0x8a/0x90
  ? srso_return_thunk+0x5/0x5f
  ? srso_return_thunk+0x5/0x5f
  ? sched_balance_rq+0x369/0x810
  ip6_route_output_flags+0xd7/0x170
  bond_ns_send_all+0xde/0x280 [bonding]
  bond_ab_arp_probe+0x296/0x320 [bonding]
  ? srso_return_thunk+0x5/0x5f
  bond_activebackup_arp_mon+0xb4/0x2c0 [bonding]
  process_one_work+0x196/0x370
  worker_thread+0x1af/0x320
  ? srso_return_thunk+0x5/0x5f
  ? __pfx_worker_thread+0x10/0x10
  kthread+0xe3/0x120
  ? __pfx_kthread+0x10/0x10
  ret_from_fork+0x199/0x260
  ? __pfx_kthread+0x10/0x10
  ret_from_fork_asm+0x1a/0x30
  </TASK>

Fix this by adding ipv6_mod_enabled() condition check in the caller.
Comment 1 gkamathe 2026-08-11 13:08:27 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081036-CVE-2026-68336-acbd@gregkh/T