[PATCH 1/2] powerpc/pseries/msi: Fix potential underflow and leak issue

[Nam Cao <namcao@linutronix.de>]

pseries_irq_domain_alloc() allocates interrupts at parent's interrupt
domain. If it fails in the progress, all allocated interrupts are
freed.

The number of successfully allocated interrupts so far is stored
"i". However, "i - 1" interrupts are freed. This is broken:

  - One interrupt is not be freed

  - If "i" is zero, "i - 1" wraps around

Correct the number of freed interrupts to 'i'.

Fixes: a5f3d2c17b07 ("powerpc/pseries/pci: Add MSI domains")
Signed-off-by: Nam Cao <namcao@linutronix.de>
Cc: stable@vger.kernel.org
---
 arch/powerpc/platforms/pseries/msi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/msi.c b/arch/powerpc/platforms/pseries/msi.c
index ee1c8c6898a3..9dc294de631f 100644
--- a/arch/powerpc/platforms/pseries/msi.c
+++ b/arch/powerpc/platforms/pseries/msi.c
@@ -593,7 +593,7 @@ static int pseries_irq_domain_alloc(struct irq_domain *domain, unsigned int virq
 
 out:
 	/* TODO: handle RTAS cleanup in ->msi_finish() ? */
-	irq_domain_free_irqs_parent(domain, virq, i - 1);
+	irq_domain_free_irqs_parent(domain, virq, i);
 	return ret;
 }
 
-- 
2.39.5