From 570540d50710ed192e98e2f7f74578c9486b6b05 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 13 Jan 2016 14:07:25 +0100 Subject: genirq: Validate action before dereferencing it in handle_irq_event_percpu() commit 71f64340fc0e changed the handling of irq_desc->action from CPU 0 CPU 1 free_irq() lock(desc) lock(desc) handle_edge_irq() if (desc->action) { handle_irq_event() action = desc->action unlock(desc) desc->action = NULL handle_irq_event_percpu(desc, action) action->xxx to CPU 0 CPU 1 free_irq() lock(desc) lock(desc) handle_edge_irq() if (desc->action) { handle_irq_event() unlock(desc) desc->action = NULL handle_irq_event_percpu(desc, action) action = desc->action action->xxx So if free_irq manages to set the action to NULL between the unlock and before the readout, we happily dereference a null pointer. We could simply revert 71f64340fc0e, but we want to preserve the better code generation. A simple solution is to change the action loop from a do {} while to a while {} loop. This is safe because we either see a valid desc->action or NULL. If the action is about to be removed it is still valid as free_irq() is blocked on synchronize_irq(). CPU 0 CPU 1 free_irq() lock(desc) lock(desc) handle_edge_irq() handle_irq_event(desc) set(INPROGRESS) unlock(desc) handle_irq_event_percpu(desc) action = desc->action desc->action = NULL while (action) { action->xxx ... action = action->next; sychronize_irq() while(INPROGRESS); lock(desc) clr(INPROGRESS) free(action) That's basically the same mechanism as we have for shared interrupts. action->next can become NULL while handle_irq_event_percpu() runs. Either it sees the action or NULL. It does not matter, because action itself cannot go away before the interrupt in progress flag has been cleared. Fixes: commit 71f64340fc0e "genirq: Remove the second parameter from handle_irq_event_percpu()" Reported-by: zyjzyj2000@gmail.com Signed-off-by: Thomas Gleixner Cc: Huang Shijie Cc: Jiang Liu Cc: Peter Zijlstra Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1601131224190.3575@nanos --- kernel/irq/handle.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c index a302cf9a2126..57bff7857e87 100644 --- a/kernel/irq/handle.c +++ b/kernel/irq/handle.c @@ -138,7 +138,8 @@ irqreturn_t handle_irq_event_percpu(struct irq_desc *desc) unsigned int flags = 0, irq = desc->irq_data.irq; struct irqaction *action = desc->action; - do { + /* action might have become NULL since we dropped the lock */ + while (action) { irqreturn_t res; trace_irq_handler_entry(irq, action); @@ -173,7 +174,7 @@ irqreturn_t handle_irq_event_percpu(struct irq_desc *desc) retval |= res; action = action->next; - } while (action); + } add_interrupt_randomness(irq, flags); -- cgit v1.2.3 From 530cbe100ef7587aa5b5ac3a4b670cda4d50e598 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Tue, 26 Jan 2016 13:52:25 +0000 Subject: irqdomain: Allow domain lookup with DOMAIN_BUS_WIRED token Let's take the (outlandish) example of an interrupt controller capable of handling both wired interrupts and PCI MSIs. With the current code, the PCI MSI domain is going to be tagged with DOMAIN_BUS_PCI_MSI, and the wired domain with DOMAIN_BUS_ANY. Things get hairy when we start looking up the domain for a wired interrupt (typically when creating it based on some firmware information - DT or ACPI). In irq_create_fwspec_mapping(), we perform the lookup using DOMAIN_BUS_ANY, which is actually used as a wildcard. This gives us one chance out of two to end up with the wrong domain, and we try to configure a wired interrupt with the MSI domain. Everything grinds to a halt pretty quickly. What we really need to do is to start looking for a domain that would uniquely identify a wired interrupt domain, and only use DOMAIN_BUS_ANY as a fallback. In order to solve this, let's introduce a new DOMAIN_BUS_WIRED token, which is going to be used exactly as described above. Of course, this depends on the irqchip to setup the domain bus_token, and nobody had to implement this so far. Only so far. Signed-off-by: Marc Zyngier Cc: Greg Kroah-Hartman Cc: Rob Herring Cc: Frank Rowand Cc: Grant Likely Cc: Thomas Petazzoni Cc: Jiang Liu Link: http://lkml.kernel.org/r/1453816347-32720-2-git-send-email-marc.zyngier@arm.com Signed-off-by: Thomas Gleixner --- include/linux/irqdomain.h | 1 + kernel/irq/irqdomain.c | 11 ++++++++--- 2 files changed, 9 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h index f64622ad02c1..04579d9fbce4 100644 --- a/include/linux/irqdomain.h +++ b/include/linux/irqdomain.h @@ -70,6 +70,7 @@ struct irq_fwspec { */ enum irq_domain_bus_token { DOMAIN_BUS_ANY = 0, + DOMAIN_BUS_WIRED, DOMAIN_BUS_PCI_MSI, DOMAIN_BUS_PLATFORM_MSI, DOMAIN_BUS_NEXUS, diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c index 8cf95de1ab3f..d75179735a28 100644 --- a/kernel/irq/irqdomain.c +++ b/kernel/irq/irqdomain.c @@ -575,10 +575,15 @@ unsigned int irq_create_fwspec_mapping(struct irq_fwspec *fwspec) unsigned int type = IRQ_TYPE_NONE; int virq; - if (fwspec->fwnode) - domain = irq_find_matching_fwnode(fwspec->fwnode, DOMAIN_BUS_ANY); - else + if (fwspec->fwnode) { + domain = irq_find_matching_fwnode(fwspec->fwnode, + DOMAIN_BUS_WIRED); + if (!domain) + domain = irq_find_matching_fwnode(fwspec->fwnode, + DOMAIN_BUS_ANY); + } else { domain = irq_default_domain; + } if (!domain) { pr_warn("no irq domain found for %s !\n", -- cgit v1.2.3