diff mbox

[tpmdd-devel,07/10] tpm: tpm2_unseal_cmd: check size of response before accessing data

Message ID 1484057900-17871-7-git-send-email-stefanb@linux.vnet.ibm.com
State New
Headers show

Commit Message

Stefan Berger Jan. 10, 2017, 2:18 p.m. UTC 
Check the size of the response before accessing data in the
response packet. This is to avoid accessing data beyond the
end of the response.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
---
 drivers/char/tpm/tpm2-cmd.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)
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Patch

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 4bcda2b..f55e876 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -689,6 +689,7 @@  static int tpm2_unseal_cmd(struct tpm_chip *chip,
 	u16 data_len;
 	u8 *data;
 	int rc;
+	u32 rlength;
 
 	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
 	if (rc)
@@ -708,8 +709,19 @@  static int tpm2_unseal_cmd(struct tpm_chip *chip,
 		rc = -EPERM;
 
 	if (!rc) {
+		rlength = be32_to_cpu(((struct tpm2_cmd *)&buf)
+					->header.out.length);
+		if (rlength < TPM_HEADER_SIZE + 4 + 2) {
+			rc = -EFAULT;
+			goto out;
+		}
 		data_len = be16_to_cpup(
 			(__be16 *) &buf.data[TPM_HEADER_SIZE + 4]);
+
+		if (rlength < TPM_HEADER_SIZE + 4 + 2 + data_len) {
+			rc = -EFAULT;
+			goto out;
+		}
 		data = &buf.data[TPM_HEADER_SIZE + 6];
 
 		memcpy(payload->key, data, data_len - 1);
@@ -717,6 +729,7 @@  static int tpm2_unseal_cmd(struct tpm_chip *chip,
 		payload->migratable = data[data_len - 1];
 	}
 
+out:
 	tpm_buf_destroy(&buf);
 	return rc;
 }