Amazon Linux AMI: CVE-2024-56658: Security patch for kernel (ALAS-2025-1970)

In the Linux kernel, the following vulnerability has been resolved:

net: defer final 'struct net' free in netns dismantle

Ilya reported a slab-use-after-free in dst_destroy [1]

Issue is in xfrm6_net_init() and xfrm4_net_init() :

They copy xfrm[46]_dst_ops_template into net->xfrm.xfrm[46]_dst_ops.

But net structure might be freed before all the dst callbacks are

called. So when dst_destroy() calls later :

if (dst->ops->destroy)

dst->ops->destroy(dst);

dst->ops points to the old net->xfrm.xfrm[46]_dst_ops, which has been freed.

See a relevant issue fixed in :

ac888d58869b ("net: do not delay dst_entries_add() in dst_release()")

A fix is to queue the 'struct net' to be freed after one

another cleanup_net() round (and existing rcu_barrier())

[1]

BUG: KASAN: slab-use-after-free in dst_destroy (net/core/dst.c:112)

Read of size 8 at addr ffff8882137ccab0 by task swapper/37/0

Dec 03 05:46:18 kernel:

CPU: 37 UID: 0 PID: 0 Comm: swapper/37 Kdump: loaded Not tainted 6.12.0 #67

Hardware name: Red Hat KVM/RHEL, BIOS 1.16.1-1.el9 04/01/2014

Call Trace:

<IRQ>

dump_stack_lvl (lib/dump_stack.c:124)

print_address_description.constprop.0 (mm/kasan/report.c:378)

? dst_destroy (net/core/dst.c:112)

print_report (mm/kasan/report.c:489)

? dst_destroy (net/core/dst.c:112)

? kasan_addr_to_slab (mm/kasan/common.c:37)

kasan_report (mm/kasan/report.c:603)

? dst_destroy (net/core/dst.c:112)

? rcu_do_batch (kernel/rcu/tree.c:2567)

dst_destroy (net/core/dst.c:112)

rcu_do_batch (kernel/rcu/tree.c:2567)

? __pfx_rcu_do_batch (kernel/rcu/tree.c:2491)

? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4339 kernel/locking/lockdep.c:4406)

rcu_core (kernel/rcu/tree.c:2825)

handle_softirqs (kernel/softirq.c:554)

__irq_exit_rcu (kernel/softirq.c:589 kernel/softirq.c:428 kernel/softirq.c:637)

irq_exit_rcu (kernel/softirq.c:651)

sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1049 arch/x86/kernel/apic/apic.c:1049)

</IRQ>

<TASK>

asm_sysvec_apic_timer_interrupt (./arch/x86/include/asm/idtentry.h:702)

RIP: 0010:default_idle (./arch/x86/include/asm/irqflags.h:37 ./arch/x86/include/asm/irqflags.h:92 arch/x86/kernel/process.c:743)

Code: 00 4d 29 c8 4c 01 c7 4c 29 c2 e9 6e ff ff ff 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66 90 0f 00 2d c7 c9 27 00 fb f4 <fa> c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 90

RSP: 0018:ffff888100d2fe00 EFLAGS: 00000246

RAX: 00000000001870ed RBX: 1ffff110201a5fc2 RCX: ffffffffb61a3e46

RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffb3d4d123

RBP: 0000000000000000 R08: 0000000000000001 R09: ffffed11c7e1835d

R10: ffff888e3f0c1aeb R11: 0000000000000000 R12: 0000000000000000

R13: ffff888100d20000 R14: dffffc0000000000 R15: 0000000000000000

? ct_kernel_exit.constprop.0 (kernel/context_tracking.c:148)

? cpuidle_idle_call (kernel/sched/idle.c:186)

default_idle_call (./include/linux/cpuidle.h:143 kernel/sched/idle.c:118)

cpuidle_idle_call (kernel/sched/idle.c:186)

? __pfx_cpuidle_idle_call (kernel/sched/idle.c:168)

? lock_release (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5848)

? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4347 kernel/locking/lockdep.c:4406)

? tsc_verify_tsc_adjust (arch/x86/kernel/tsc_sync.c:59)

do_idle (kernel/sched/idle.c:326)

cpu_startup_entry (kernel/sched/idle.c:423 (discriminator 1))

start_secondary (arch/x86/kernel/smpboot.c:202 arch/x86/kernel/smpboot.c:282)

? __pfx_start_secondary (arch/x86/kernel/smpboot.c:232)

? soft_restart_cpu (arch/x86/kernel/head_64.S:452)

common_startup_64 (arch/x86/kernel/head_64.S:414)

</TASK>

Dec 03 05:46:18 kernel:

Allocated by task 12184:

kasan_save_stack (mm/kasan/common.c:48)

kasan_save_track (./arch/x86/include/asm/current.h:49 mm/kasan/common.c:60 mm/kasan/common.c:69)

__kasan_slab_alloc (mm/kasan/common.c:319 mm/kasan/common.c:345)

kmem_cache_alloc_noprof (mm/slub.c:4085 mm/slub.c:4134 mm/slub.c:4141)

copy_net_ns (net/core/net_namespace.c:421 net/core/net_namespace.c:480)

create_new_namespaces

---truncated---