[v1] of: overlay: fix null pointer dereferencing in find_dup_cset_node_entry() and find_dup_cset_prop()

[PATCH] of: overlay: fix null pointer dereferencing in find_dup_cset_node_entry() and find_dup_cset_prop()

Posted by ruanjinjie 3 years, 2 months ago

when kmalloc() fail to allocate memory in kasprintf(), fn_1 or fn_2 will
be NULL, strcmp() will cause null pointer dereference.

Fixes: 2fe0e8769df9 ("of: overlay: check prevents multiple fragments touching same property")
Signed-off-by: ruanjinjie <ruanjinjie@huawei.com>
---
 drivers/of/overlay.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index bd8ff4df723d..49c066b51148 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -545,6 +545,11 @@ static int find_dup_cset_node_entry(struct overlay_changeset *ovcs,
 
 		fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
 		fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
+		if (!fn_1 || !fn_2) {
+			kfree(fn_1);
+			kfree(fn_2);
+			return -ENOMEM;
+		}
 		node_path_match = !strcmp(fn_1, fn_2);
 		kfree(fn_1);
 		kfree(fn_2);
@@ -580,6 +585,11 @@ static int find_dup_cset_prop(struct overlay_changeset *ovcs,
 
 		fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
 		fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
+		if (!fn_1 || !fn_2) {
+			kfree(fn_1);
+			kfree(fn_2);
+			return -ENOMEM;
+		}
 		node_path_match = !strcmp(fn_1, fn_2);
 		kfree(fn_1);
 		kfree(fn_2);
-- 
2.25.1

Re: [PATCH] of: overlay: fix null pointer dereferencing in find_dup_cset_node_entry() and find_dup_cset_prop()

Posted by Rob Herring 3 years, 2 months ago

On Tue, Dec 06, 2022 at 04:36:57PM +0800, ruanjinjie wrote:
> when kmalloc() fail to allocate memory in kasprintf(), fn_1 or fn_2 will
> be NULL, strcmp() will cause null pointer dereference.
> 
> Fixes: 2fe0e8769df9 ("of: overlay: check prevents multiple fragments touching same property")
> Signed-off-by: ruanjinjie <ruanjinjie@huawei.com>
> ---
>  drivers/of/overlay.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
> index bd8ff4df723d..49c066b51148 100644
> --- a/drivers/of/overlay.c
> +++ b/drivers/of/overlay.c
> @@ -545,6 +545,11 @@ static int find_dup_cset_node_entry(struct overlay_changeset *ovcs,
>  
>  		fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
>  		fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
> +		if (!fn_1 || !fn_2) {
> +			kfree(fn_1);
> +			kfree(fn_2);
> +			return -ENOMEM;
> +		}
>  		node_path_match = !strcmp(fn_1, fn_2);

We don't actually care what the return code is, so just change this to:

node_path_match = !fn_1 || !fn_2 || !strcmp(fn_1, fn_2);

>  		kfree(fn_1);
>  		kfree(fn_2);
> @@ -580,6 +585,11 @@ static int find_dup_cset_prop(struct overlay_changeset *ovcs,
>  
>  		fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
>  		fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
> +		if (!fn_1 || !fn_2) {
> +			kfree(fn_1);
> +			kfree(fn_2);
> +			return -ENOMEM;
> +		}
>  		node_path_match = !strcmp(fn_1, fn_2);
>  		kfree(fn_1);
>  		kfree(fn_2);
> -- 
> 2.25.1
> 
>

Re: [PATCH] of: overlay: fix null pointer dereferencing in find_dup_cset_node_entry() and find_dup_cset_prop()

Posted by Ruan Jinjie 3 years, 1 month ago


On 2022/12/10 4:59, Rob Herring wrote:
> On Tue, Dec 06, 2022 at 04:36:57PM +0800, ruanjinjie wrote:
>> when kmalloc() fail to allocate memory in kasprintf(), fn_1 or fn_2 will
>> be NULL, strcmp() will cause null pointer dereference.
>>
>> Fixes: 2fe0e8769df9 ("of: overlay: check prevents multiple fragments touching same property")
>> Signed-off-by: ruanjinjie <ruanjinjie@huawei.com>
>> ---
>>  drivers/of/overlay.c | 10 ++++++++++
>>  1 file changed, 10 insertions(+)
>>
>> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
>> index bd8ff4df723d..49c066b51148 100644
>> --- a/drivers/of/overlay.c
>> +++ b/drivers/of/overlay.c
>> @@ -545,6 +545,11 @@ static int find_dup_cset_node_entry(struct overlay_changeset *ovcs,
>>  
>>  		fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
>>  		fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
>> +		if (!fn_1 || !fn_2) {
>> +			kfree(fn_1);
>> +			kfree(fn_2);
>> +			return -ENOMEM;
>> +		}
>>  		node_path_match = !strcmp(fn_1, fn_2);
> 
> We don't actually care what the return code is, so just change this to:
> 
> node_path_match = !fn_1 || !fn_2 || !strcmp(fn_1, fn_2);
Thank you very much!I'll give the v2 patch soon.
> 
>>  		kfree(fn_1);
>>  		kfree(fn_2);
>> @@ -580,6 +585,11 @@ static int find_dup_cset_prop(struct overlay_changeset *ovcs,
>>  
>>  		fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
>>  		fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
>> +		if (!fn_1 || !fn_2) {
>> +			kfree(fn_1);
>> +			kfree(fn_2);
>> +			return -ENOMEM;
>> +		}
>>  		node_path_match = !strcmp(fn_1, fn_2);
>>  		kfree(fn_1);
>>  		kfree(fn_2);
>> -- 
>> 2.25.1
>>
>>
>