KASAN reported a slab-out-of-bounds read of size 1 in
kdf_create_vcrat_image_cpu().

This occurs when, for example, when on an x86_64 with a single NUMA node
because kfd_fill_iolink_info_for_cpu() is a no-op, but afterwards the
sub_type_hdr->length, which is out-of-bounds, is read and multiplied by
entries. Fortunately, entries is 0 in this case so the overall
crat_table->length is still correct.

This refactors the helper functions to accept the crat_table directly
and calculate the table entry pointer based on the current table length.
This allows us to avoid an out-of-bounds read and hopefully makes the
pointer arithmetic clearer. It should have no functional change beyond
removing the out-of-bounds read.

Fixes: b7b6c38529c9 ("drm/amdkfd: Calculate CPU VCRAT size dynamically (v2)")
Signed-off-by: Jeremy Cline <jcl...@redhat.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_crat.c | 86 +++++++++++++--------------
 1 file changed, 40 insertions(+), 46 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_crat.c 
b/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
index 8cac497c2c45..e50db2c0f4ee 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
@@ -829,21 +829,24 @@ int kfd_create_crat_image_acpi(void **crat_image, size_t 
*size)
 /* kfd_fill_cu_for_cpu - Fill in Compute info for the given CPU NUMA node
  *
  *     @numa_node_id: CPU NUMA node id
- *     @avail_size: Available size in the memory
- *     @sub_type_hdr: Memory into which compute info will be filled in
+ *     @avail_size: Available space in bytes at the end of the @crat_table.
+ *     @crat_table: The CRAT table to append the Compute info to;
+ *             on success the table length and total_entries count is updated.
  *
  *     Return 0 if successful else return -ve value
  */
 static int kfd_fill_cu_for_cpu(int numa_node_id, int *avail_size,
-                               int proximity_domain,
-                               struct crat_subtype_computeunit *sub_type_hdr)
+                               struct crat_header *crat_table)
 {
        const struct cpumask *cpumask;
+       struct crat_subtype_computeunit *sub_type_hdr;
 
        *avail_size -= sizeof(struct crat_subtype_computeunit);
        if (*avail_size < 0)
                return -ENOMEM;
 
+       sub_type_hdr = (typeof(sub_type_hdr))((char *)crat_table +
+               crat_table->length);
        memset(sub_type_hdr, 0, sizeof(struct crat_subtype_computeunit));
 
        /* Fill in subtype header data */
@@ -855,36 +858,42 @@ static int kfd_fill_cu_for_cpu(int numa_node_id, int 
*avail_size,
 
        /* Fill in CU data */
        sub_type_hdr->flags |= CRAT_CU_FLAGS_CPU_PRESENT;
-       sub_type_hdr->proximity_domain = proximity_domain;
+       sub_type_hdr->proximity_domain = crat_table->num_domains;
        sub_type_hdr->processor_id_low = kfd_numa_node_to_apic_id(numa_node_id);
        if (sub_type_hdr->processor_id_low == -1)
                return -EINVAL;
 
        sub_type_hdr->num_cpu_cores = cpumask_weight(cpumask);
 
+       crat_table->length += sub_type_hdr->length;
+       crat_table->total_entries++;
+
        return 0;
 }
 
 /* kfd_fill_mem_info_for_cpu - Fill in Memory info for the given CPU NUMA node
  *
  *     @numa_node_id: CPU NUMA node id
- *     @avail_size: Available size in the memory
- *     @sub_type_hdr: Memory into which compute info will be filled in
+ *     @avail_size: Available space in bytes at the end of the @crat_table.
+ *     @crat_table: The CRAT table to append the Memory info to;
+ *             on success the table length and total_entries count is updated.
  *
  *     Return 0 if successful else return -ve value
  */
 static int kfd_fill_mem_info_for_cpu(int numa_node_id, int *avail_size,
-                       int proximity_domain,
-                       struct crat_subtype_memory *sub_type_hdr)
+                       struct crat_header *crat_table)
 {
        uint64_t mem_in_bytes = 0;
        pg_data_t *pgdat;
        int zone_type;
+       struct crat_subtype_memory *sub_type_hdr;
 
        *avail_size -= sizeof(struct crat_subtype_memory);
        if (*avail_size < 0)
                return -ENOMEM;
 
+       sub_type_hdr = (typeof(sub_type_hdr))((char *)crat_table +
+               crat_table->length);
        memset(sub_type_hdr, 0, sizeof(struct crat_subtype_memory));
 
        /* Fill in subtype header data */
@@ -905,27 +914,37 @@ static int kfd_fill_mem_info_for_cpu(int numa_node_id, 
int *avail_size,
 
        sub_type_hdr->length_low = lower_32_bits(mem_in_bytes);
        sub_type_hdr->length_high = upper_32_bits(mem_in_bytes);
-       sub_type_hdr->proximity_domain = proximity_domain;
+       sub_type_hdr->proximity_domain = crat_table->num_domains;
+
+       crat_table->length += sub_type_hdr->length;
+       crat_table->total_entries++;
 
        return 0;
 }
 
 #ifdef CONFIG_X86_64
+/* kfd_fill_iolink_info_for_cpu() - Add IO link info to a Virtual CRAT
+ *
+ * @numa_node_id: The NUMA node ID for the CPU; as from for_each_online_node()
+ * @avail_size: Available space in bytes at the end of the @crat_table.
+ * @crat_table: The CRAT table to append the IO link info to; on success the
+ *              table length and total_entries count is updated.
+ *
+ * Return: 0 if successful else return -ve value
+ */
 static int kfd_fill_iolink_info_for_cpu(int numa_node_id, int *avail_size,
-                               uint32_t *num_entries,
-                               struct crat_subtype_iolink *sub_type_hdr)
+                               struct crat_header *crat_table)
 {
        int nid;
        struct cpuinfo_x86 *c = &cpu_data(0);
        uint8_t link_type;
+       struct crat_subtype_iolink *sub_type_hdr;
 
        if (c->x86_vendor == X86_VENDOR_AMD)
                link_type = CRAT_IOLINK_TYPE_HYPERTRANSPORT;
        else
                link_type = CRAT_IOLINK_TYPE_QPI_1_1;
 
-       *num_entries = 0;
-
        /* Create IO links from this node to other CPU nodes */
        for_each_online_node(nid) {
                if (nid == numa_node_id) /* node itself */
@@ -935,6 +954,8 @@ static int kfd_fill_iolink_info_for_cpu(int numa_node_id, 
int *avail_size,
                if (*avail_size < 0)
                        return -ENOMEM;
 
+               sub_type_hdr = (typeof(sub_type_hdr))((char *)crat_table +
+                       crat_table->length);
                memset(sub_type_hdr, 0, sizeof(struct crat_subtype_iolink));
 
                /* Fill in subtype header data */
@@ -947,8 +968,8 @@ static int kfd_fill_iolink_info_for_cpu(int numa_node_id, 
int *avail_size,
                sub_type_hdr->proximity_domain_to = nid;
                sub_type_hdr->io_interface_type = link_type;
 
-               (*num_entries)++;
-               sub_type_hdr++;
+               crat_table->length += sub_type_hdr->length;
+               crat_table->total_entries++;
        }
 
        return 0;
@@ -966,12 +987,8 @@ static int kfd_create_vcrat_image_cpu(void *pcrat_image, 
size_t *size)
        struct crat_header *crat_table = (struct crat_header *)pcrat_image;
        struct acpi_table_header *acpi_table;
        acpi_status status;
-       struct crat_subtype_generic *sub_type_hdr;
        int avail_size = *size;
        int numa_node_id;
-#ifdef CONFIG_X86_64
-       uint32_t entries = 0;
-#endif
        int ret = 0;
 
        if (!pcrat_image)
@@ -1003,48 +1020,25 @@ static int kfd_create_vcrat_image_cpu(void 
*pcrat_image, size_t *size)
        crat_table->total_entries = 0;
        crat_table->num_domains = 0;
 
-       sub_type_hdr = (struct crat_subtype_generic *)(crat_table+1);
-
        for_each_online_node(numa_node_id) {
                if (kfd_numa_node_to_apic_id(numa_node_id) == -1)
                        continue;
 
                /* Fill in Subtype: Compute Unit */
-               ret = kfd_fill_cu_for_cpu(numa_node_id, &avail_size,
-                       crat_table->num_domains,
-                       (struct crat_subtype_computeunit *)sub_type_hdr);
+               ret = kfd_fill_cu_for_cpu(numa_node_id, &avail_size, 
crat_table);
                if (ret < 0)
                        return ret;
-               crat_table->length += sub_type_hdr->length;
-               crat_table->total_entries++;
-
-               sub_type_hdr = (typeof(sub_type_hdr))((char *)sub_type_hdr +
-                       sub_type_hdr->length);
 
                /* Fill in Subtype: Memory */
-               ret = kfd_fill_mem_info_for_cpu(numa_node_id, &avail_size,
-                       crat_table->num_domains,
-                       (struct crat_subtype_memory *)sub_type_hdr);
+               ret = kfd_fill_mem_info_for_cpu(numa_node_id, &avail_size, 
crat_table);
                if (ret < 0)
                        return ret;
-               crat_table->length += sub_type_hdr->length;
-               crat_table->total_entries++;
-
-               sub_type_hdr = (typeof(sub_type_hdr))((char *)sub_type_hdr +
-                       sub_type_hdr->length);
 
                /* Fill in Subtype: IO Link */
 #ifdef CONFIG_X86_64
-               ret = kfd_fill_iolink_info_for_cpu(numa_node_id, &avail_size,
-                               &entries,
-                               (struct crat_subtype_iolink *)sub_type_hdr);
+               ret = kfd_fill_iolink_info_for_cpu(numa_node_id, &avail_size, 
crat_table);
                if (ret < 0)
                        return ret;
-               crat_table->length += (sub_type_hdr->length * entries);
-               crat_table->total_entries += entries;
-
-               sub_type_hdr = (typeof(sub_type_hdr))((char *)sub_type_hdr +
-                               sub_type_hdr->length * entries);
 #else
                pr_info("IO link not available for non x86 platforms\n");
 #endif
-- 
2.28.0

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