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Message-ID: <20210109022612.GB248768@xps13>
Date: Fri, 8 Jan 2021 21:26:12 -0500
From: Jeremy Cline <jcline@...hat.com>
To: Felix Kuehling <felix.kuehling@....com>
Cc: Alex Deucher <alexander.deucher@....com>,
Christian König <christian.koenig@....com>,
David Airlie <airlied@...ux.ie>,
Daniel Vetter <daniel@...ll.ch>,
Kent Russell <kent.russell@....com>,
amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/amdkfd: Fix out-of-bounds read in
kdf_create_vcrat_image_cpu()
On Fri, Jan 08, 2021 at 06:46:17PM -0500, Felix Kuehling wrote:
> Am 2021-01-08 um 11:31 a.m. schrieb Jeremy Cline:
> > 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.
>
> That's a pretty big change to fix that. Wouldn't it be enough to add a
> simple check after calling kfd_fill_iolink_info_for_cpu:
>
> if (entries) {
> crat_table->length += (sub_type_hdr->length * entries);
> crat_table->total_entries += entries;
> }
>
> Or change the output parameters of the kfd_fill_..._for_cpu functions
> from num_entries to size_filled, so the caller doesn't need to read
> sub_type_hdr->length any more.
>
For sure. I felt like this was a bit tidier afterwards, but that's an
opinion and not one I hold strongly. I'll look at preparing a smaller fix
next week.
Thanks,
Jeremy
> >
> > 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 <jcline@...hat.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
>
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