[U-Boot] [PATCH v1] tpm: Fix uclass_first_device error handling

[Mario Six]

uclass_first_device might return NULL for the device despite a zero
return code. Currently, this might lead to null pointer dereferencing,
since the returned device is not properly checked.

Hence, always check if the device returned from uclass_first_device is
NULL and return -ENODEV if it is.

Signed-off-by: Mario Six <mario.six at gdsys.cc>
---
 lib/tpm.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/tpm.c b/lib/tpm.c
index f428d45..42aea0a 100644
--- a/lib/tpm.c
+++ b/lib/tpm.c
@@ -245,6 +245,8 @@ static uint32_t tpm_sendrecv_command(const void *command,
 	ret = uclass_first_device(UCLASS_TPM, &dev);
 	if (ret)
 		return ret;
+	if (!dev)
+		return -ENODEV;
 	err = tpm_xfer(dev, command, tpm_command_size(command),
 		       response, &response_length);

@@ -262,8 +264,10 @@ int tpm_init(void)
 	struct udevice *dev;

 	err = uclass_first_device(UCLASS_TPM, &dev);
-	if (err || !dev)
+	if (err)
 		return err;
+	if (!dev)
+		return -ENODEV;
 	return tpm_open(dev);
 }

--
2.7.0.GIT