Under certain conditions uninitialized memory will be accessed.
As described by TCG Trusted Platform Module Library Specification,
rev. 1.59 (Part 3: Commands), if a TPM2_GetCapability is received,
requesting a capability, the TPM in Field Upgrade mode may return a
zero length list.
Check the property count in tpm2_get_tpm_pt().
Fixes: 2ab3241161b3 ("tpm: migrate tpm2_get_tpm_pt() to use struct tpm_buf")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Stefan Mahnke-Hartmann <stefan.mahnke-hartmann@xxxxxxxxxxxx>
---
drivers/char/tpm/tpm2-cmd.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 4704fa553098..e62a644ce26b 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -400,7 +400,10 @@ ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id, u32 *value,
if (!rc) {
out = (struct tpm2_get_cap_out *)
&buf.data[TPM_HEADER_SIZE];
- *value = be32_to_cpu(out->value);
+ if (be32_to_cpu(out->property_cnt) > 0)
+ *value = be32_to_cpu(out->value);
+ else
+ rc = -ENODATA;
}
tpm_buf_destroy(&buf);
return rc;
--
2.25.1
