linux-kernel - [PATCH v2 2/2] x86/xen: Fix memory leak in xen_init_lock

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Date:   Wed, 23 Nov 2022 23:58:58 +0800
From:   Xiu Jianfeng <xiujianfeng@...wei.com>
To:     <jgross@...e.com>, <boris.ostrovsky@...cle.com>,
        <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
        <dave.hansen@...ux.intel.com>, <hpa@...or.com>, <jeremy@...p.org>
CC:     <x86@...nel.org>, <xen-devel@...ts.xenproject.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 2/2] x86/xen: Fix memory leak in xen_init_lock_cpu()

In xen_init_lock_cpu(), the @name has allocated new string by kasprintf(),
if bind_ipi_to_irqhandler() fails, it should be freed, otherwise may lead
to a memory leak issue, fix it.

Fixes: 2d9e1e2f58b5 ("xen: implement Xen-specific spinlocks")
Signed-off-by: Xiu Jianfeng <xiujianfeng@...wei.com>
---
 arch/x86/xen/spinlock.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
index 043c73dfd2c9..5c6fc16e4b92 100644
--- a/arch/x86/xen/spinlock.c
+++ b/arch/x86/xen/spinlock.c
@@ -75,6 +75,7 @@ void xen_init_lock_cpu(int cpu)
 	     cpu, per_cpu(lock_kicker_irq, cpu));
 
 	name = kasprintf(GFP_KERNEL, "spinlock%d", cpu);
+	per_cpu(irq_name, cpu) = name;
 	irq = bind_ipi_to_irqhandler(XEN_SPIN_UNLOCK_VECTOR,
 				     cpu,
 				     dummy_handler,
@@ -85,7 +86,6 @@ void xen_init_lock_cpu(int cpu)
 	if (irq >= 0) {
 		disable_irq(irq); /* make sure it's never delivered */
 		per_cpu(lock_kicker_irq, cpu) = irq;
-		per_cpu(irq_name, cpu) = name;
 	}
 
 	printk("cpu %d spinlock event irq %d\n", cpu, irq);
@@ -98,6 +98,8 @@ void xen_uninit_lock_cpu(int cpu)
 	if (!xen_pvspin)
 		return;
 
+	kfree(per_cpu(irq_name, cpu));
+	per_cpu(irq_name, cpu) = NULL;
 	/*
 	 * When booting the kernel with 'mitigations=auto,nosmt', the secondary
 	 * CPUs are not activated, and lock_kicker_irq is not initialized.
@@ -108,8 +110,6 @@ void xen_uninit_lock_cpu(int cpu)
 
 	unbind_from_irqhandler(irq, NULL);
 	per_cpu(lock_kicker_irq, cpu) = -1;
-	kfree(per_cpu(irq_name, cpu));
-	per_cpu(irq_name, cpu) = NULL;
 }
 
 PV_CALLEE_SAVE_REGS_THUNK(xen_vcpu_stolen);
-- 
2.17.1