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From: "Liang, Kan" <kan.liang@linux.intel.com>
To: 13145886936@163.com, tglx@linutronix.de, bp@alien8.de, x86@kernel.org
Cc: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
	gushengxian <gushengxian@yulong.com>,
	"Antonov, Alexander" <alexander.antonov@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH] x86: eas should not be NULL when it is referenced
Date: Thu, 24 Jun 2021 15:06:02 -0400	[thread overview]
Message-ID: <f313e0d9-b18e-5dd8-cadf-ee0a689f20ea@linux.intel.com> (raw)
In-Reply-To: <40e66cf9-398b-20d7-ce4d-433be6e08921@linux.intel.com>


Oops, forgot to add Peter.

On 6/24/2021 3:03 PM, Liang, Kan wrote:
> 
> Hi Shengxian,
> 
> Thanks for the patch.
> 
> On 6/24/2021 3:04 AM, 13145886936@163.com wrote:
>> From: gushengxian <gushengxian@yulong.com>
>>
>> "eas" should not be NULL when it is referenced.
>>
> 
> I think the NULL pointer dereference of eas should not happen, because 
> die is -1 if eas is NULL. But the whole error handling path looks fragile.
> 
> We already fixed one issue caused by it in commit ID f797f05d917f 
> ("perf/x86/intel/uncore: Fix for iio mapping on Skylake Server")
> https://lore.kernel.org/lkml/160149233331.7002.10919231011379055356.tip-bot2@tip-bot2/ 
> 
> 
> Maybe something as below?
> 
>  From 3de81ba3b04262ef3346297d82f6c4ffb4af7029 Mon Sep 17 00:00:00 2001
> From: Kan Liang <kan.liang@linux.intel.com>
> Date: Thu, 24 Jun 2021 11:17:57 -0700
> Subject: [PATCH] perf/x86/intel/uncore: Clean up error handling path of 
> iio mapping
> 
> The error handling path of iio mapping looks fragile. We already fixed
> one issue caused by it, commit ID f797f05d917f ("perf/x86/intel/uncore:
> Fix for iio mapping on Skylake Server"). Clean up the error handling
> path and make the code robust.
> 
> Reported-by: gushengxian <gushengxian@yulong.com>
> Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
> ---
>   arch/x86/events/intel/uncore_snbep.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/events/intel/uncore_snbep.c 
> b/arch/x86/events/intel/uncore_snbep.c
> index 7622762..6d4a5a9 100644
> --- a/arch/x86/events/intel/uncore_snbep.c
> +++ b/arch/x86/events/intel/uncore_snbep.c
> @@ -3802,11 +3802,11 @@ pmu_iio_set_mapping(struct intel_uncore_type 
> *type, struct attribute_group *ag)
>       /* One more for NULL. */
>       attrs = kcalloc((uncore_max_dies() + 1), sizeof(*attrs), GFP_KERNEL);
>       if (!attrs)
> -        goto err;
> +        goto clear_topology;
> 
>       eas = kcalloc(uncore_max_dies(), sizeof(*eas), GFP_KERNEL);
>       if (!eas)
> -        goto err;
> +        goto clear_attrs;
> 
>       for (die = 0; die < uncore_max_dies(); die++) {
>           sprintf(buf, "die%ld", die);
> @@ -3827,7 +3827,9 @@ pmu_iio_set_mapping(struct intel_uncore_type 
> *type, struct attribute_group *ag)
>       for (; die >= 0; die--)
>           kfree(eas[die].attr.attr.name);
>       kfree(eas);
> +clear_attrs:
>       kfree(attrs);
> +clear_topology:
>       kfree(type->topology);
>   clear_attr_update:
>       type->attr_update = NULL;

  reply	other threads:[~2021-06-24 19:06 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-24  7:04 13145886936
2021-06-24  7:24 ` Peter Zijlstra
2021-06-24 19:03 ` Liang, Kan
2021-06-24 19:06   ` Liang, Kan [this message]
2021-06-25 13:33     ` Alexander Antonov
2021-06-25 14:11       ` Liang, Kan
2021-06-25 14:26         ` Alexander Antonov

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