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Subject[PATCH 2/2] platform/x86/amd/pmf: Fix possible out-of-bound memory accesses
Date
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.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
---
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 70d09103ab18..f2f9204b3a11 100644
--- a/drivers/platform/x86/amd/pmf/tee-if.c
+++ b/drivers/platform/x86/amd/pmf/tee-if.c
@@ -249,12 +249,18 @@ static int amd_pmf_start_policy_engine(struct amd_pmf_dev *dev)
u32 cookie, length;
int res;

+ if (dev->policy_sz < POLICY_COOKIE_LEN)
+ return -EINVAL;
+
cookie = dev->policy_buf[POLICY_COOKIE_OFFSET];
length = dev->policy_buf[POLICY_COOKIE_LEN];

if (cookie != POLICY_SIGN_COOKIE || !length)
return -EINVAL;

+ if (dev->policy_sz < length + 512)
+ return -EINVAL;
+
/* Update the actual length */
dev->policy_sz = length + 512;
res = amd_pmf_invoke_cmd_init(dev);
--
2.39.2

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