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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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eddf3e9c7c
The following crash was observed:
Unable to handle kernel NULL pointer dereference at 0000000000000158
Internal error: Oops: 96000004 [#1] SMP
pc : resend_irqs+0x68/0xb0
lr : resend_irqs+0x64/0xb0
...
Call trace:
resend_irqs+0x68/0xb0
tasklet_action_common.isra.6+0x84/0x138
tasklet_action+0x2c/0x38
__do_softirq+0x120/0x324
run_ksoftirqd+0x44/0x60
smpboot_thread_fn+0x1ac/0x1e8
kthread+0x134/0x138
ret_from_fork+0x10/0x18
The reason for this is that the interrupt resend mechanism happens in soft
interrupt context, which is a asynchronous mechanism versus other
operations on interrupts. free_irq() does not take resend handling into
account. Thus, the irq descriptor might be already freed before the resend
tasklet is executed. resend_irqs() does not check the return value of the
interrupt descriptor lookup and derefences the return value
unconditionally.
1):
__setup_irq
irq_startup
check_irq_resend // activate softirq to handle resend irq
2):
irq_domain_free_irqs
irq_free_descs
free_desc
call_rcu(&desc->rcu, delayed_free_desc)
3):
__do_softirq
tasklet_action
resend_irqs
desc = irq_to_desc(irq)
desc->handle_irq(desc) // desc is NULL --> Ooops
Fix this by adding a NULL pointer check in resend_irqs() before derefencing
the irq descriptor.
Fixes: a4633adcdb ("[PATCH] genirq: add genirq sw IRQ-retrigger")
Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1630ae13-5c8e-901e-de09-e740b6a426a7@huawei.com
103 lines
2.5 KiB
C
103 lines
2.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
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* Copyright (C) 2005-2006, Thomas Gleixner
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*
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* This file contains the IRQ-resend code
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*
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* If the interrupt is waiting to be processed, we try to re-run it.
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* We can't directly run it from here since the caller might be in an
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* interrupt-protected region. Not all irq controller chips can
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* retrigger interrupts at the hardware level, so in those cases
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* we allow the resending of IRQs via a tasklet.
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*/
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#include <linux/irq.h>
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#include <linux/module.h>
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#include <linux/random.h>
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#include <linux/interrupt.h>
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#include "internals.h"
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#ifdef CONFIG_HARDIRQS_SW_RESEND
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/* Bitmap to handle software resend of interrupts: */
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static DECLARE_BITMAP(irqs_resend, IRQ_BITMAP_BITS);
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/*
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* Run software resends of IRQ's
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*/
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static void resend_irqs(unsigned long arg)
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{
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struct irq_desc *desc;
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int irq;
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while (!bitmap_empty(irqs_resend, nr_irqs)) {
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irq = find_first_bit(irqs_resend, nr_irqs);
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clear_bit(irq, irqs_resend);
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desc = irq_to_desc(irq);
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if (!desc)
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continue;
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local_irq_disable();
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desc->handle_irq(desc);
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local_irq_enable();
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}
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}
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/* Tasklet to handle resend: */
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static DECLARE_TASKLET(resend_tasklet, resend_irqs, 0);
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#endif
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/*
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* IRQ resend
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*
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* Is called with interrupts disabled and desc->lock held.
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*/
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void check_irq_resend(struct irq_desc *desc)
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{
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/*
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* We do not resend level type interrupts. Level type
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* interrupts are resent by hardware when they are still
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* active. Clear the pending bit so suspend/resume does not
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* get confused.
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*/
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if (irq_settings_is_level(desc)) {
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desc->istate &= ~IRQS_PENDING;
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return;
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}
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if (desc->istate & IRQS_REPLAY)
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return;
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if (desc->istate & IRQS_PENDING) {
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desc->istate &= ~IRQS_PENDING;
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desc->istate |= IRQS_REPLAY;
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if (!desc->irq_data.chip->irq_retrigger ||
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!desc->irq_data.chip->irq_retrigger(&desc->irq_data)) {
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#ifdef CONFIG_HARDIRQS_SW_RESEND
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unsigned int irq = irq_desc_get_irq(desc);
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/*
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* If the interrupt is running in the thread
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* context of the parent irq we need to be
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* careful, because we cannot trigger it
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* directly.
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*/
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if (irq_settings_is_nested_thread(desc)) {
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/*
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* If the parent_irq is valid, we
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* retrigger the parent, otherwise we
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* do nothing.
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*/
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if (!desc->parent_irq)
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return;
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irq = desc->parent_irq;
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}
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/* Set it pending and activate the softirq: */
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set_bit(irq, irqs_resend);
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tasklet_schedule(&resend_tasklet);
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#endif
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}
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}
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}
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