Re: [PATCH] genirq:Dereference desc after null pointer check
From: Dan Carpenter
Date: Tue Jul 17 2018 - 08:26:19 EST
Hi RAGHU,
Thank you for the patch! Perhaps something to improve:
url: https://github.com/0day-ci/linux/commits/RAGHU-Halharvi/genirq-Dereference-desc-after-null-pointer-check/20180717-150842
smatch warnings:
kernel/irq/manage.c:1571 __free_irq() error: uninitialized symbol 'irq'.
# https://github.com/0day-ci/linux/commit/3ebb02d34bcb1c8111a79856326bca85fb3321eb
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 3ebb02d34bcb1c8111a79856326bca85fb3321eb
vim +/irq +1571 kernel/irq/manage.c
d3c60047 Thomas Gleixner 2008-10-16 1560
cbf94f06 Magnus Damm 2009-03-12 1561 /*
cbf94f06 Magnus Damm 2009-03-12 1562 * Internal function to unregister an irqaction - used to free
cbf94f06 Magnus Damm 2009-03-12 1563 * regular and special interrupts that are part of the architecture.
^1da177e Linus Torvalds 2005-04-16 1564 */
83ac4ca9 Uwe Kleine König 2018-03-19 1565 static struct irqaction *__free_irq(struct irq_desc *desc, void *dev_id)
^1da177e Linus Torvalds 2005-04-16 1566 {
3ebb02d3 RAGHU Halharvi 2018-07-17 1567 unsigned int irq;
f17c7545 Ingo Molnar 2009-02-17 1568 struct irqaction *action, **action_ptr;
^1da177e Linus Torvalds 2005-04-16 1569 unsigned long flags;
^1da177e Linus Torvalds 2005-04-16 1570
ae88a23b Ingo Molnar 2009-02-15 @1571 WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
^^^
Not initialized.
7d94f7ca Yinghai Lu 2008-08-19 1572
7d94f7ca Yinghai Lu 2008-08-19 1573 if (!desc)
f21cfb25 Magnus Damm 2009-03-12 1574 return NULL;
^1da177e Linus Torvalds 2005-04-16 1575
3ebb02d3 RAGHU Halharvi 2018-07-17 1576 irq = desc->irq_data.irq;
9114014c Thomas Gleixner 2017-06-29 1577 mutex_lock(&desc->request_mutex);
abc7e40c Thomas Gleixner 2015-12-13 1578 chip_bus_lock(desc);
239007b8 Thomas Gleixner 2009-11-17 1579 raw_spin_lock_irqsave(&desc->lock, flags);
ae88a23b Ingo Molnar 2009-02-15 1580
ae88a23b Ingo Molnar 2009-02-15 1581 /*
ae88a23b Ingo Molnar 2009-02-15 1582 * There can be multiple actions per IRQ descriptor, find the right
ae88a23b Ingo Molnar 2009-02-15 1583 * one based on the dev_id:
ae88a23b Ingo Molnar 2009-02-15 1584 */
f17c7545 Ingo Molnar 2009-02-17 1585 action_ptr = &desc->action;
^1da177e Linus Torvalds 2005-04-16 1586 for (;;) {
f17c7545 Ingo Molnar 2009-02-17 1587 action = *action_ptr;
^1da177e Linus Torvalds 2005-04-16 1588
ae88a23b Ingo Molnar 2009-02-15 1589 if (!action) {
ae88a23b Ingo Molnar 2009-02-15 1590 WARN(1, "Trying to free already-free IRQ %d\n", irq);
239007b8 Thomas Gleixner 2009-11-17 1591 raw_spin_unlock_irqrestore(&desc->lock, flags);
abc7e40c Thomas Gleixner 2015-12-13 1592 chip_bus_sync_unlock(desc);
19d39a38 Thomas Gleixner 2017-07-11 1593 mutex_unlock(&desc->request_mutex);
f21cfb25 Magnus Damm 2009-03-12 1594 return NULL;
ae88a23b Ingo Molnar 2009-02-15 1595 }
^1da177e Linus Torvalds 2005-04-16 1596
8316e381 Ingo Molnar 2009-02-17 1597 if (action->dev_id == dev_id)
ae88a23b Ingo Molnar 2009-02-15 1598 break;
f17c7545 Ingo Molnar 2009-02-17 1599 action_ptr = &action->next;
ae88a23b Ingo Molnar 2009-02-15 1600 }
^1da177e Linus Torvalds 2005-04-16 1601
ae88a23b Ingo Molnar 2009-02-15 1602 /* Found it - now remove it from the list of entries: */
f17c7545 Ingo Molnar 2009-02-17 1603 *action_ptr = action->next;
dbce706e Paolo 'Blaisorblade' Giarrusso 2005-06-21 1604
cab303be Thomas Gleixner 2014-08-28 1605 irq_pm_remove_action(desc, action);
cab303be Thomas Gleixner 2014-08-28 1606
ae88a23b Ingo Molnar 2009-02-15 1607 /* If this was the last handler, shut down the IRQ line: */
c1bacbae Thomas Gleixner 2014-03-08 1608 if (!desc->action) {
e9849777 Thomas Gleixner 2015-10-09 1609 irq_settings_clr_disable_unlazy(desc);
46999238 Thomas Gleixner 2011-02-02 1610 irq_shutdown(desc);
c1bacbae Thomas Gleixner 2014-03-08 1611 }
3aa551c9 Thomas Gleixner 2009-03-23 1612
:::::: The code at line 1571 was first introduced by commit
:::::: ae88a23b32fa7e0dc9fa7ce735966e68eb41b0bc irq: refactor and clean up the free_irq() code flow
:::::: TO: Ingo Molnar <mingo@xxxxxxx>
:::::: CC: Ingo Molnar <mingo@xxxxxxx>
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