CVE-2025-68322

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

parisc: Avoid crash due to unaligned access in unwinder

Guenter Roeck reported this kernel crash on his emulated B160L machine:

Starting network: udhcpc: started, v1.36.1

Backtrace:

[<104320d4>] unwind_once+0x1c/0x5c

[<10434a00>] walk_stackframe.isra.0+0x74/0xb8

[<10434a6c>] arch_stack_walk+0x28/0x38

[<104e5efc>] stack_trace_save+0x48/0x5c

[<105d1bdc>] set_track_prepare+0x44/0x6c

[<105d9c80>] ___slab_alloc+0xfc4/0x1024

[<105d9d38>] __slab_alloc.isra.0+0x58/0x90

[<105dc80c>] kmem_cache_alloc_noprof+0x2ac/0x4a0

[<105b8e54>] __anon_vma_prepare+0x60/0x280

[<105a823c>] __vmf_anon_prepare+0x68/0x94

[<105a8b34>] do_wp_page+0x8cc/0xf10

[<105aad88>] handle_mm_fault+0x6c0/0xf08

[<10425568>] do_page_fault+0x110/0x440

[<10427938>] handle_interruption+0x184/0x748

[<11178398>] schedule+0x4c/0x190

BUG: spinlock recursion on CPU#0, ifconfig/2420

lock: terminate_lock.2+0x0/0x1c, .magic: dead4ead, .owner: ifconfig/2420, .owner_cpu: 0

While creating the stack trace, the unwinder uses the stack pointer to guess

the previous frame to read the previous stack pointer from memory. The crash

happens, because the unwinder tries to read from unaligned memory and as such

triggers the unalignment trap handler which then leads to the spinlock

recursion and finally to a deadlock.

Fix it by checking the alignment before accessing the memory.