The length of the policy buffer is not validated before accessing it,
which means that multiple out-of-bounds memory accesses can occur.
This is especially bad since userspace can load policy binaries over
debugfs.
Compile-tested only.
Fixes: 7c45534afa44 ("platform/x86/amd/pmf: Add support for PMF Policy Binary")
Signed-off-by: Armin Wolf <W_Armin@xxxxxx>
---
drivers/platform/x86/amd/pmf/tee-if.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/platform/x86/amd/pmf/tee-if.c b/drivers/platform/x86/amd/pmf/tee-if.c
index 71ea7eefc211..75370431a82e 100644
--- a/drivers/platform/x86/amd/pmf/tee-if.c
+++ b/drivers/platform/x86/amd/pmf/tee-if.c
@@ -249,11 +249,17 @@ static int amd_pmf_start_policy_engine(struct amd_pmf_dev *dev)
struct cookie_header *header;
int res;
+ if (dev->policy_sz < POLICY_COOKIE_OFFSET + sizeof(*header))
+ return -EINVAL;
+
header = (struct cookie_header *)(dev->policy_buf + POLICY_COOKIE_OFFSET);
if (header->sign != POLICY_SIGN_COOKIE || !header->length)
return -EINVAL;
+ if (dev->policy_sz < header->length + 512)
+ return -EINVAL;
+
/* Update the actual length */
dev->policy_sz = header->length + 512;
res = amd_pmf_invoke_cmd_init(dev);
--
2.39.2
