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x86/xen: avoid freeing static 'name' when kasprintf() fails

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In case kasprintf() fails in xen_setup_timer() we assign name to the
static string "<timer kasprintf failed>". We, however, don't check
that fact before issuing kfree() in xen_teardown_timer(), kernel is
supposed to crash with 'kernel BUG at mm/slub.c:3341!'

Solve the issue by making name a fixed length string inside struct
xen_clock_event_device. 16 bytes should be enough.

Suggested-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
This commit is contained in:
Vitaly Kuznetsov 2015-01-05 16:27:51 +01:00 • committed by David Vrabel
parent a97dae1a2e
commit 7be0772d19
1 changed files with 5 additions and 11 deletions
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16
arch/x86/xen/time.c
View file

@ -391,7 +391,7 @@ static const struct clock_event_device *xen_clockevent =
struct xen_clock_event_device { struct xen_clock_event_device {
struct clock_event_device evt; struct clock_event_device evt;
char *name; char name[16];
}; };
static DEFINE_PER_CPU(struct xen_clock_event_device, xen_clock_events) = { .evt.irq = -1 }; static DEFINE_PER_CPU(struct xen_clock_event_device, xen_clock_events) = { .evt.irq = -1 };
@ -420,39 +420,33 @@ void xen_teardown_timer(int cpu)
if (evt->irq >= 0) { if (evt->irq >= 0) {
unbind_from_irqhandler(evt->irq, NULL); unbind_from_irqhandler(evt->irq, NULL);
evt->irq = -1; evt->irq = -1;
kfree(per_cpu(xen_clock_events, cpu).name);
per_cpu(xen_clock_events, cpu).name = NULL;
} }
} }
void xen_setup_timer(int cpu) void xen_setup_timer(int cpu)
{ {
char *name; struct xen_clock_event_device *xevt = &per_cpu(xen_clock_events, cpu);
struct clock_event_device *evt; struct clock_event_device *evt = &xevt->evt;
int irq; int irq;
evt = &per_cpu(xen_clock_events, cpu).evt;
WARN(evt->irq >= 0, "IRQ%d for CPU%d is already allocated\n", evt->irq, cpu); WARN(evt->irq >= 0, "IRQ%d for CPU%d is already allocated\n", evt->irq, cpu);
if (evt->irq >= 0) if (evt->irq >= 0)
xen_teardown_timer(cpu); xen_teardown_timer(cpu);
printk(KERN_INFO "installing Xen timer for CPU %d\n", cpu); printk(KERN_INFO "installing Xen timer for CPU %d\n", cpu);
name = kasprintf(GFP_KERNEL, "timer%d", cpu); snprintf(xevt->name, sizeof(xevt->name), "timer%d", cpu);
if (!name)
name = "<timer kasprintf failed>";
irq = bind_virq_to_irqhandler(VIRQ_TIMER, cpu, xen_timer_interrupt, irq = bind_virq_to_irqhandler(VIRQ_TIMER, cpu, xen_timer_interrupt,
IRQF_PERCPU|IRQF_NOBALANCING|IRQF_TIMER| IRQF_PERCPU|IRQF_NOBALANCING|IRQF_TIMER|
IRQF_FORCE_RESUME|IRQF_EARLY_RESUME, IRQF_FORCE_RESUME|IRQF_EARLY_RESUME,
name, NULL); xevt->name, NULL);
(void)xen_set_irq_priority(irq, XEN_IRQ_PRIORITY_MAX); (void)xen_set_irq_priority(irq, XEN_IRQ_PRIORITY_MAX);
memcpy(evt, xen_clockevent, sizeof(*evt)); memcpy(evt, xen_clockevent, sizeof(*evt));
evt->cpumask = cpumask_of(cpu); evt->cpumask = cpumask_of(cpu);
evt->irq = irq; evt->irq = irq;
per_cpu(xen_clock_events, cpu).name = name;
} }