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From: Stefan Berger <stefanb@linux.ibm.com>
Date: Mon, 20 Feb 2023 14:41:10 -0500
Subject: tpm2: Check size of buffer before accessing it (CVE-2023-1017 &
-1018)
Origin: https://github.com/stefanberger/libtpms/commit/324dbb4c27ae789c73b69dbf4611242267919dd4
Bug-Debian: https://bugs.debian.org/1032420
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2023-1018
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2023-1017
Check that there are sufficient bytes in the buffer before reading the
cipherSize from it. Also, reduce the bufferSize variable by the number
of bytes that make up the cipherSize to avoid reading and writing bytes
beyond the buffer in subsequent steps that do in-place decryption.
This fixes CVE-2023-1017 & CVE-2023-1018.
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
---
src/tpm2/CryptUtil.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/src/tpm2/CryptUtil.c b/src/tpm2/CryptUtil.c
index 002fde0987a9..8fae5b6903ca 100644
--- a/src/tpm2/CryptUtil.c
+++ b/src/tpm2/CryptUtil.c
@@ -830,6 +830,10 @@ CryptParameterDecryption(
+ sizeof(session->sessionKey.t.buffer)));
TPM2B_HMAC_KEY key; // decryption key
UINT32 cipherSize = 0; // size of cipher text
+
+ if (leadingSizeInByte > bufferSize)
+ return TPM_RC_INSUFFICIENT;
+
// Retrieve encrypted data size.
if(leadingSizeInByte == 2)
{
@@ -837,6 +841,7 @@ CryptParameterDecryption(
// data to be decrypted
cipherSize = (UINT32)BYTE_ARRAY_TO_UINT16(buffer);
buffer = &buffer[2]; // advance the buffer
+ bufferSize -= 2;
}
#ifdef TPM4B
else if(leadingSizeInByte == 4)
@@ -844,6 +849,7 @@ CryptParameterDecryption(
// the leading size is four bytes so get the four byte size field
cipherSize = BYTE_ARRAY_TO_UINT32(buffer);
buffer = &buffer[4]; //advance pointer
+ bufferSize -= 4;
}
#endif
else
--
2.39.2
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