linux-kernel - Re: [PATCH 2/2] iommu/vt-d: Use BUG_ON to check NULL value of 'table'

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <3e75f9de-4c67-93aa-9fb4-28da9849dd48@linux.intel.com>
Date:   Wed, 31 May 2023 11:26:55 +0800
From:   Baolu Lu <baolu.lu@...ux.intel.com>
To:     Yanfei Xu <yanfei.xu@...el.com>, dwmw2@...radead.org,
        joro@...tes.org, will@...nel.org, robin.murphy@....com
Cc:     baolu.lu@...ux.intel.com, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] iommu/vt-d: Use BUG_ON to check NULL value of 'table'

On 5/30/23 5:25 PM, Yanfei Xu wrote:
> Checking NULL value of 'table' variable deserves a BUG_ON as the
> following code will trigger a crash by dereferencing the NULL
> 'table' pointer. Crash in advance with BUG_ON to avoid WARN_ON
> plus NULL pointer dereferencing can simplify the crash log.
> 
> Signed-off-by: Yanfei Xu<yanfei.xu@...el.com>
> ---
>   drivers/iommu/intel/iommu.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index e98f1b122b49..8aa3bfdb7f95 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -1944,7 +1944,7 @@ static int domain_context_mapping_one(struct dmar_domain *domain,
>   	if (sm_supported(iommu)) {
>   		unsigned long pds;
>   
> -		WARN_ON(!table);
> +		BUG_ON(!table);

BUG_ON() is not recommended. Perhaps,

		if (!table)
			-ENODEV;

?

Best regards,
baolu