CVE-2025-71132 in Linux
Sumário
de VulDB • 29/05/2026
No kernel do Linux, a seguinte vulnerabilidade foi resolvida:
smc91x: corrigir contexto de irq quebrado no PREEMPT_RT
Quando o smc91x.c é compilado com PREEMPT_RT, ocorre o seguinte erro no FVP_RevC:
[ 13.055000] smc91x LNRO0003:00 eth0: link up, 10Mbps, half-duplex, lpa 0x0000
[ 13.062137] BUG: workqueue leaked atomic, lock or RCU: kworker/2:1[106]
[ 13.062137] preempt=0x00000000 lock=0->0 RCU=0->1 workfn=mld_ifc_work
[ 13.062266] C
** replaying previous printk message ** [ 13.062266] CPU: 2 UID: 0 PID: 106 Comm: kworker/2:1 Not tainted 6.18.0-dirty #179 PREEMPT_{RT,(full)}
[ 13.062353] Hardware name: , BIOS
[ 13.062382] Workqueue: mld mld_ifc_work
[ 13.062469] Call trace:
[ 13.062494] show_stack+0x24/0x40 (C)
[ 13.062602] __dump_stack+0x28/0x48
[ 13.062710] dump_stack_lvl+0x7c/0xb0
[ 13.062818] dump_stack+0x18/0x34
[ 13.062926] process_scheduled_works+0x294/0x450
[ 13.063043] worker_thread+0x260/0x3d8
[ 13.063124] kthread+0x1c4/0x228
[ 13.063235] ret_from_fork+0x10/0x20
Isso ocorre porque smc_special_trylock() desativa as IRQs mesmo no PREEMPT_RT, mas smc_special_unlock() não restaura as IRQs no PREEMPT_RT. A razão é que smc_special_unlock() chama spin_unlock_irqrestore(), e rcu_read_unlock_bh() em __dev_queue_xmit() não pode invocar rcu_read_unlock() através de __local_bh_enable_ip() quando current->softirq_disable_cnt se torna zero.
Para resolver este problema, substitua smc_special_trylock() por spin_trylock_irqsave().
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