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Message-Id: <20240227145500.299683-2-W_Armin@gmx.de>
Date: Tue, 27 Feb 2024 15:55:00 +0100
From: Armin Wolf <W_Armin@....de>
To: Shyam-sundar.S-k@....com
Cc: hdegoede@...hat.com,
ilpo.jarvinen@...ux.intel.com,
platform-driver-x86@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 2/2] platform/x86/amd/pmf: Fix possible out-of-bound memory accesses
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@....de>
---
Changes since v1:
- check if the policy buffer also has enough room for storing the length
---
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 b3491268b6a0..09e3c620a9c7 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 + sizeof(length))
+ return -EINVAL;
+
cookie = *(u32 *)(dev->policy_buf + POLICY_COOKIE_OFFSET);
length = *(u32 *)(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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