linux-kernel - [tip:x86/urgent] x86/apic/vector: Fix off by one in error path

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Message-ID: <tip-45d55e7bac4028af93f5fa324e69958a0b868e96@git.kernel.org>
Date:   Wed, 17 Jan 2018 03:15:50 -0800
From:   tip-bot for Thomas Gleixner <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     keith.busch@...el.com, mingo@...nel.org,
        linux-kernel@...r.kernel.org, hpa@...or.com, tglx@...utronix.de
Subject: [tip:x86/urgent] x86/apic/vector: Fix off by one in error path

Commit-ID:  45d55e7bac4028af93f5fa324e69958a0b868e96
Gitweb:     https://git.kernel.org/tip/45d55e7bac4028af93f5fa324e69958a0b868e96
Author:     Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Tue, 16 Jan 2018 12:20:18 +0100
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Wed, 17 Jan 2018 12:11:36 +0100

x86/apic/vector: Fix off by one in error path

Keith reported the following warning:

WARNING: CPU: 28 PID: 1420 at kernel/irq/matrix.c:222 irq_matrix_remove_managed+0x10f/0x120
  x86_vector_free_irqs+0xa1/0x180
  x86_vector_alloc_irqs+0x1e4/0x3a0
  msi_domain_alloc+0x62/0x130

The reason for this is that if the vector allocation fails the error
handling code tries to free the failed vector as well, which causes the
above imbalance warning to trigger.

Adjust the error path to handle this correctly.

Fixes: b5dc8e6c21e7 ("x86/irq: Use hierarchical irqdomain to manage CPU interrupt vectors")
Reported-by: Keith Busch <keith.busch@...el.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Tested-by: Keith Busch <keith.busch@...el.com>
Cc: stable@...r.kernel.org
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1801161217300.1823@nanos

---
 arch/x86/kernel/apic/vector.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index f8b03bb..3cc471b 100644
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -542,14 +542,17 @@ static int x86_vector_alloc_irqs(struct irq_domain *domain, unsigned int virq,
 
 		err = assign_irq_vector_policy(irqd, info);
 		trace_vector_setup(virq + i, false, err);
-		if (err)
+		if (err) {
+			irqd->chip_data = NULL;
+			free_apic_chip_data(apicd);
 			goto error;
+		}
 	}
 
 	return 0;
 
 error:
-	x86_vector_free_irqs(domain, virq, i + 1);
+	x86_vector_free_irqs(domain, virq, i);
 	return err;
 }