Coverity: kfd_parse_subtype_cache(): Memory - corruptions

[Ma, Jun]

Thanks, I will send the fix patch.

Regards,
Ma Jun

On 11/5/2022 4:40 AM, Felix Kuehling wrote:
> On 2022-11-04 15:41, coverity-bot wrote:
>> Hello!
>>
>> This is an experimental semi-automated report about issues detected by
>> Coverity from a scan of next-20221104 as part of the linux-next scan project:
>> https://scan.coverity.com/projects/linux-next-weekly-scan
>>
>> You're getting this email because you were associated with the identified
>> lines of code (noted below) that were touched by commits:
>>
>>    Fri Dec 8 23:08:59 2017 -0500
>>      3a87177eb141 ("drm/amdkfd: Add topology support for dGPUs")
>>
>> Coverity reported the following:
>>
>> *** CID 1527133:  Memory - corruptions  (OVERRUN)
>> drivers/gpu/drm/amd/amdkfd/kfd_crat.c:1113 in kfd_parse_subtype_cache()
>> 1107     			props->cache_size = cache->cache_size;
>> 1108     			props->cacheline_size = cache->cache_line_size;
>> 1109     			props->cachelines_per_tag = cache->lines_per_tag;
>> 1110     			props->cache_assoc = cache->associativity;
>> 1111     			props->cache_latency = cache->cache_latency;
>> 1112
>> vvv     CID 1527133:  Memory - corruptions  (OVERRUN)
>> vvv     Overrunning array "cache->sibling_map" of 32 bytes by passing it to a function which accesses it at byte offset 63 using argument "64UL". [Note: The source code implementation of the function has been overridden by a builtin model.]
>> 1113     			memcpy(props->sibling_map, cache->sibling_map,
>> 1114     					sizeof(props->sibling_map));
>> 1115
>> 1116     			/* set the sibling_map_size as 32 for CRAT from ACPI */
>> 1117     			props->sibling_map_size = CRAT_SIBLINGMAP_SIZE;
>> 1118
>>
>> If this is a false positive, please let us know so we can mark it as
>> such, or teach the Coverity rules to be smarter. If not, please make
>> sure fixes get into linux-next. :) For patches fixing this, please
>> include these lines (but double-check the "Fixes" first):
>>
>> Reported-by: coverity-bot <keescook+coverity-bot at chromium.org>
>> Addresses-Coverity-ID: 1527133 ("Memory - corruptions")
>> Fixes: 3a87177eb141 ("drm/amdkfd: Add topology support for dGPUs")
>>
>> I'm not sure why this suddenly appeared after 5 years, but the read
>> over-run looks legit:
> 
> 
> I think this was introduced by a more recent patch that was in fact 
> meant to fix an array overrun on HW that is outgrowing the CRAT sibling 
> map size:
>
>> commit 0938fbeb6f53fc44bc9b19784dee28496e68ba0c
>> Author: Ma Jun <Jun.Ma2 at amd.com>
>> Date:   Wed Nov 2 15:53:26 2022 +0800
>>
>>     drm/amdkfd: Fix the warning of array-index-out-of-bounds
>>
>>     For some GPUs with more CUs, the original sibling_map[32]
>>     in struct crat_subtype_cache is not enough
>>     to save the cache information when create the VCRAT table,
>>     so skip filling the struct crat_subtype_cache info instead
>>     fill struct kfd_cache_properties directly to fix this problem.
>>
>>     Signed-off-by: Ma Jun <Jun.Ma2 at amd.com>
>>     Reviewed-by: Felix Kuehling <Felix.Kuehling at amd.com>
>>     Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
> I added Ma Jun to the email.
> 
> Regards,
>    Felix
> 
> 
>>
>> struct crat_subtype_cache {
>>          ...
>>          uint8_t         sibling_map[CRAT_SIBLINGMAP_SIZE];
>>
>> #define CRAT_SIBLINGMAP_SIZE    32
>>
>>
>> struct kfd_cache_properties {
>>          ...
>>          uint8_t                 sibling_map[CACHE_SIBLINGMAP_SIZE];
>>
>> #define CACHE_SIBLINGMAP_SIZE 64
>>
>> Thanks for your attention!
>>