powerpc/powernv/pci: Fix underflow and leak issue

pnv_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: 0fcfe2247e75 ("powerpc/powernv/pci: Add MSI domains")
Signed-off-by: Nam Cao <namcao@linutronix.de>
Cc: stable@vger.kernel.org
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/70f8debe8688e0b467367db769b71c20146a836d.1754300646.git.namcao@linutronix.de

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index d8ccf2c9b98ad02d99d633764d1b2902a684ab26..0166bf39ce1e52dfaa554d6637ca2f0fe079c981 100644 (file)
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -1854,7 +1854,7 @@ static int pnv_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
        return 0;
 
 out:
-       irq_domain_free_irqs_parent(domain, virq, i - 1);
+       irq_domain_free_irqs_parent(domain, virq, i);
        msi_bitmap_free_hwirqs(&phb->msi_bmp, hwirq, nr_irqs);
        return ret;
 }