linux-kernel - Re: [PATCH][next] ACPI: APEI: EINJ: Fix check and iounmap of uninitialized pointer p

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Message-ID: <04752c56-d6fb-4fab-99d2-93449c8c5d8d@gmail.com>
Date: Wed, 25 Jun 2025 22:43:26 +0100
From: "Colin King (gmail)" <colin.i.king@...il.com>
To: Ira Weiny <ira.weiny@...el.com>, "Rafael J . Wysocki"
 <rafael@...nel.org>, Len Brown <lenb@...nel.org>,
 James Morse <james.morse@....com>, Tony Luck <tony.luck@...el.com>,
 Borislav Petkov <bp@...en8.de>, linux-acpi@...r.kernel.org
Cc: kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] ACPI: APEI: EINJ: Fix check and iounmap of
 uninitialized pointer p

On 25/06/2025 22:40, Ira Weiny wrote:
> Colin Ian King wrote:
>> In the case where a request_mem_region call fails and pointer r is null
>> the error exit path via label 'out' will check for a non-null pointer
>> p and try to iounmap it. However, pointer p has not been assigned a
>> value at this point, so it may potentially contain any garbage value.
>> Fix this by ensuring pointer p is initialized to NULL.
>>
>> Fixes: 1a35c88302a3 ("ACPI: APEI: EINJ: Fix kernel test sparse warnings")
>> Signed-off-by: Colin Ian King <colin.i.king@...il.com>
>> ---
>>   drivers/acpi/apei/einj-core.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/acpi/apei/einj-core.c b/drivers/acpi/apei/einj-core.c
>> index 7930acd1d3f3..fc801587df8e 100644
>> --- a/drivers/acpi/apei/einj-core.c
>> +++ b/drivers/acpi/apei/einj-core.c
>> @@ -401,7 +401,7 @@ static int __einj_error_trigger(u64 trigger_paddr, u32 type,
>>   	u32 table_size;
>>   	int rc = -EIO;
>>   	struct acpi_generic_address *trigger_param_region = NULL;
>> -	struct acpi_einj_trigger __iomem *p;
>> +	struct acpi_einj_trigger __iomem *p = NULL;
> 
> Apparently my review of these was pretty weak...  :-/
> 
> That said; Why not skip a goto as well?

Because the goto uses a shared return path and hence reduces the amount 
of return epilogue used in the generated code.

Colin

> 
> Ira
> 
> diff --git a/drivers/acpi/apei/einj-core.c b/drivers/acpi/apei/einj-core.c
> index d6d7e36e3647..fae01795e7f6 100644
> --- a/drivers/acpi/apei/einj-core.c
> +++ b/drivers/acpi/apei/einj-core.c
> @@ -410,7 +410,7 @@ static int __einj_error_trigger(u64 trigger_paddr, u32 type,
>                         (unsigned long long)trigger_paddr,
>                         (unsigned long long)trigger_paddr +
>                              sizeof(trigger_tab) - 1);
> -               goto out;
> +               return -EIO;
>          }
>          p = ioremap_cache(trigger_paddr, sizeof(*p));
>          if (!p) {
> @@ -502,7 +502,6 @@ static int __einj_error_trigger(u64 trigger_paddr, u32 type,
>                             table_size - sizeof(trigger_tab));
>   out_rel_header:
>          release_mem_region(trigger_paddr, sizeof(trigger_tab));
> -out:
>          if (p)
>                  iounmap(p);
>   


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