linux-kernel - [PATCH] clk: zynq: Prevent null pointer dereference caused by kmalloc failure

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Message-Id: <20240214073318.82573-1-duoming@zju.edu.cn>
Date: Wed, 14 Feb 2024 15:33:18 +0800
From: Duoming Zhou <duoming@....edu.cn>
To: linux-kernel@...r.kernel.org
Cc: mturquette@...libre.com,
	sboyd@...nel.org,
	michal.simek@....com,
	linux-clk@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Duoming Zhou <duoming@....edu.cn>
Subject: [PATCH] clk: zynq: Prevent null pointer dereference caused by kmalloc failure

The kmalloc in zynq_clk_setup will return null if the
physical memory has run out. As a result, if we use
snprintf to write data to the null address, the null
pointer dereference bug will happen.

The required memory is only 11 bytes, so this patch
adds a "__GFP_NOFAIL" flag in kmalloc in order that
the kmalloc will never return with failure.

Fixes: 0ee52b157b8e ("clk: zynq: Add clock controller driver")
Signed-off-by: Duoming Zhou <duoming@....edu.cn>
---
 drivers/clk/zynq/clkc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/zynq/clkc.c b/drivers/clk/zynq/clkc.c
index 7bdeaff2bfd..7621c2f0046 100644
--- a/drivers/clk/zynq/clkc.c
+++ b/drivers/clk/zynq/clkc.c
@@ -427,7 +427,7 @@ static void __init zynq_clk_setup(struct device_node *np)
 			SLCR_GEM1_CLK_CTRL, 0, 0, &gem1clk_lock);
 
 	tmp = strlen("mio_clk_00x");
-	clk_name = kmalloc(tmp, GFP_KERNEL);
+	clk_name = kmalloc(tmp, GFP_KERNEL | __GFP_NOFAIL);
 	for (i = 0; i < NUM_MIO_PINS; i++) {
 		int idx;
 
-- 
2.17.1