[PATCH 5.10 092/199] drm/amdkfd: Fix out-of-bounds read in kdf_create_vcrat_image_cpu()

Greg Kroah-Hartman
2021-01-26T09:49:21Z

From: Jeremy Cline <jcline@redhat.com>

[ Upstream commit 8b335bff643f3b39935c7377dbcd361c5b605d98 ]

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.

Check if there were any entries before de-referencing sub_type_hdr which
may be pointing to out-of-bounds memory.

Fixes: b7b6c38529c9 ("drm/amdkfd: Calculate CPU VCRAT size dynamically (v2)")
Suggested-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Jeremy Cline <jcline@redhat.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/amd/amdkfd/kfd_crat.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_crat.c b/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
index d7f67620f57ba..31d793ee0836e 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
@@ -1034,11 +1034,14 @@ static int kfd_create_vcrat_image_cpu(void *pcrat_image, size_t *size)
(struct crat_subtype_iolink *)sub_type_hdr);
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);
+ if (entries) {
+ 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
--
2.27.0