linux-kernel - [PATCH 6/6] irq: Potentially 'offset out of size' bug

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Date:   Fri, 10 Sep 2021 03:26:12 +0000
From:   Jiang Jiasheng <jiasheng@...as.ac.cn>
To:     tglx@...utronix.de
Cc:     linux-kernel@...r.kernel.org, Jiang Jiasheng <jiasheng@...as.ac.cn>
Subject: [PATCH 6/6] irq: Potentially 'offset out of size' bug

The find_next_bit() use nr_irqs as size, and using it without
any check might cause its returned value out of the size

Signed-off-by: Jiang Jiasheng <jiasheng@...as.ac.cn>
---
 kernel/irq/irqdesc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 4a617d73..5bb310a 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -820,7 +820,8 @@ EXPORT_SYMBOL_GPL(__irq_alloc_descs);
  */
 unsigned int irq_get_next_irq(unsigned int offset)
 {
-	return find_next_bit(allocated_irqs, nr_irqs, offset);
+	offset = find_next_bit(allocated_irqs, nr_irqs, offset);
+	return offset < nr_irqs ? offset : nr_irqs;
 }
 
 struct irq_desc *
-- 
2.7.4