Subject: Coverity: kfd_parse_subtype_cache(): Memory - corruptions

From: coverity-bot <[email-masked]>
Date: Fri, 4 Nov 2022 12:41:01 -0700

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 <[email-masked]>
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:

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!

-- 
Coverity-bot