2022-03-25 18:38:25

by Xiaoke Wang

Subject: [PATCH] ARM: mvebu: check the validation of memory allocation

From: Xiaoke Wang <[email protected]>

kzalloc() and kstrdup() are memory allocation functions which can return
NULL when some internal memory errors happen. So it is better to check
the return value of them to prevent potential wrong memory access or
memory leak.

Signed-off-by: Xiaoke Wang <[email protected]>
---
arch/arm/mach-mvebu/board-v7.c | 8 ++++++++
arch/arm/mach-mvebu/coherency.c | 6 ++++++
2 files changed, 14 insertions(+)

diff --git a/arch/arm/mach-mvebu/board-v7.c b/arch/arm/mach-mvebu/board-v7.c
index d2df5ef..86d1f4e 100644
--- a/arch/arm/mach-mvebu/board-v7.c
+++ b/arch/arm/mach-mvebu/board-v7.c
@@ -128,11 +128,19 @@ 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);
}
diff --git a/arch/arm/mach-mvebu/coherency.c b/arch/arm/mach-mvebu/coherency.c
index 49e3c8d..eb6b349 100644
--- a/arch/arm/mach-mvebu/coherency.c
+++ b/arch/arm/mach-mvebu/coherency.c
@@ -194,7 +194,13 @@ static void __init armada_375_380_coherency_init(struct device_node *np)
struct property *p;

p = kzalloc(sizeof(*p), GFP_KERNEL);
+ if (!p)
+ continue;
p->name = kstrdup("arm,io-coherent", GFP_KERNEL);
+ if (!p->name) {
+ kfree(p);
+ continue;
+ }
of_add_property(cache_dn, p);
}
}
--

2022-04-30 15:32:30

by Russell King (Oracle)

Subject: Re: [PATCH] ARM: mvebu: check the validation of memory allocation

On Fri, Mar 25, 2022 at 04:55:18PM +0800, [email protected] wrote:
> From: Xiaoke Wang <[email protected]>
>
> kzalloc() and kstrdup() are memory allocation functions which can return
> NULL when some internal memory errors happen. So it is better to check
> the return value of them to prevent potential wrong memory access or
> memory leak.

Are these failures silent, or will they be reported in the kernel log to
make their failure obvious to those who debug the kernel?

--
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2022-05-02 12:20:53

by Xiaoke Wang

Subject: Re: [PATCH] ARM: mvebu: check the validation of memory allocation

On Friday, April 29, 2022 11:19 PM +0800, [email protected] wrote:
> Are these failures silent, or will they be reported in the kernel log to
> make their failure obvious to those who debug the kernel?

According to chapter 14 of the coding style document:
"These generic allocation functions all emit a stack dump on failure when used
without __GFP_NOWARN so there is no use in emitting an additional failure
message when NULL is returned."

I think that these failures are not silent since __GFP_NOWARN is not
enabled.

Regards,
Xiaoke Wang