[PATCH] ARM: mvebu: Prevent null pointer dereference caused by kzalloc failure

[PATCH] ARM: mvebu: Prevent null pointer dereference caused by kzalloc failure

[Duoming Zhou]

The kzalloc() in i2c_quirk() will return null if the physical
memory has run out. As a result, if we dereference the new_compat
pointer, the null pointer dereference bug will happen.

This patch adds a check to avoid null pointer dereference.

Fixes: 5fd62066d290 ("ARM: mvebu: Add thermal quirk for the Armada 375 DB board")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
---
 arch/arm/mach-mvebu/board-v7.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm/mach-mvebu/board-v7.c b/arch/arm/mach-mvebu/board-v7.c
index fd5d0c8ff69..7d2cb12e349 100644
--- a/arch/arm/mach-mvebu/board-v7.c
+++ b/arch/arm/mach-mvebu/board-v7.c
@@ -125,6 +125,8 @@ static void __init i2c_quirk(void)
 		struct property *new_compat;
 
 		new_compat = kzalloc(sizeof(*new_compat), GFP_KERNEL);
+		if (!new_compat)
+			continue;
 
 		new_compat->name = kstrdup("compatible", GFP_KERNEL);
 		new_compat->length = sizeof("marvell,mv78230-a0-i2c");
-- 
2.17.1


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Re: [PATCH] ARM: mvebu: Prevent null pointer dereference caused by kzalloc failure

[Russell King (Oracle)]

On Sun, Feb 25, 2024 at 02:04:01PM +0800, Duoming Zhou wrote:
> The kzalloc() in i2c_quirk() will return null if the physical
> memory has run out. As a result, if we dereference the new_compat
> pointer, the null pointer dereference bug will happen.
> 
> This patch adds a check to avoid null pointer dereference.

Yet again another janitorial patch that is Way too focused on a single
issue, rather than analysing the code and proposing the best fix. :(

What if the two kstrdup() fail?

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Re: [PATCH] ARM: mvebu: Prevent null pointer dereference caused by kzalloc failure

[duoming]

On Sun, 25 Feb 2024 11:29:53 +0000 Russell King (Oracle) wrote:
> > The kzalloc() in i2c_quirk() will return null if the physical
> > memory has run out. As a result, if we dereference the new_compat
> > pointer, the null pointer dereference bug will happen.
> > 
> > This patch adds a check to avoid null pointer dereference.
> 
> Yet again another janitorial patch that is Way too focused on a single
> issue, rather than analysing the code and proposing the best fix. :(
> 
> What if the two kstrdup() fail?

Thank you for your suggestions, I will also add a check to judge
whether two kstrdup() fail. The detail is shown below:

@@ -125,12 +125,20 @@ static void __init i2c_quirk(void)
                struct property *new_compat;

                new_compat = kzalloc(sizeof(*new_compat), GFP_KERNEL);
+               if(!new_compat)
+                       continue;

                new_compat->name = kstrdup("compatible", GFP_KERNEL);
                new_compat->length = sizeof("marvell,mv78230-a0-i2c");
                new_compat->value = kstrdup("marvell,mv78230-a0-i2c",
                                                GFP_KERNEL);

+               if (!new_compat->name || !new_compat->value) {
+                       kfree(new_compat->name);
+                       kfree(new_compat->value);
+                       kfree(new_compat);
+                       continue;
+               }
                of_update_property(np, new_compat);
        }
 }

Best regards,
Duoming Zhou
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