linux-kernel - Re: [PATCH v2] drm/amdgpu: Fix possible NULL pointer dereference

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Message-ID: <44f29433-1fe7-7d6d-616b-3f6755d2f9f3@huawei.com>
Date: Tue, 29 Oct 2024 20:36:16 +0800
From: Li Huafei <lihuafei1@...wei.com>
To: Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	<alexander.deucher@....com>, <lijo.lazar@....com>
CC: <christian.koenig@....com>, <Xinhui.Pan@....com>, <airlied@...il.com>,
	<simona@...ll.ch>, <Hawking.Zhang@....com>, <yifan1.zhang@....com>,
	<Likun.Gao@....com>, <Tim.Huang@....com>, <pratap.nirujogi@....com>,
	<victorchengchi.lu@....com>, <Jun.Ma2@....com>, <le.ma@....com>,
	<amd-gfx@...ts.freedesktop.org>, <dri-devel@...ts.freedesktop.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] drm/amdgpu: Fix possible NULL pointer dereference



On 2024/10/29 16:18, Christophe JAILLET wrote:
> Le 29/10/2024 à 11:18, Li Huafei a écrit :
>> Fix the potential NULL pointer dereference on mem_ranges in
>> amdgpu_discovery_get_nps_info(). Additionally, assign the output
>> parameters nps_type and range_cnt after the kvzalloc() call to prevent
>> modifying the output parameters in case of an error return.
>>
>> Fixes: b194d21b9bcc ("drm/amdgpu: Use NPS ranges from discovery table")
>> Signed-off-by: Li Huafei <lihuafei1@...wei.com>
>> ---
>> Changes in v2:
>>   - kvzalloc() call uses 'nps_info->v1.count' instead of '*range_cnt'
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c | 8 +++++---
>>   1 file changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
>> index 4bd61c169ca8..9a0b1b208a9d 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
>> @@ -1757,11 +1757,13 @@ int amdgpu_discovery_get_nps_info(struct
>> amdgpu_device *adev,
>>         switch (le16_to_cpu(nps_info->v1.header.version_major)) {
>>       case 1:
>> -        *nps_type = nps_info->v1.nps_type;
>> -        *range_cnt = nps_info->v1.count;
>>           mem_ranges = kvzalloc(
> 
> Not strictly related to your fix, but this could also be kvcalloc() to
> avoid potential overflow in the multiplication.
> 

Good suggestion! I added this modification in v3:

v3: https://lore.kernel.org/lkml/20241029202758.2764535-1-lihuafei1@huawei.com/T/#u

Lijo, I've added your Reviewed-by tag in v3. If you have any questions about the kvcalloc() modification, please let me know.

Thanks,
Huafei
> CJ
> 
>> -            *range_cnt * sizeof(struct amdgpu_gmc_memrange),
>> +            nps_info->v1.count * sizeof(struct amdgpu_gmc_memrange),
>>               GFP_KERNEL);
>> +        if (!mem_ranges)
>> +            return -ENOMEM;
>> +        *nps_type = nps_info->v1.nps_type;
>> +        *range_cnt = nps_info->v1.count;
>>           for (i = 0; i < *range_cnt; i++) {
>>               mem_ranges[i].base_address =
>>                   nps_info->v1.instance_info[i].base_address;
> 
> 
> .