[U-Boot] [PATCH v2] 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.

We switch to uclass_first_device_err to make sure that the returned device is
valid.

Signed-off-by: Mario Six <mario.six at gdsys.cc>
Cc: Simon Glass <sjg at chromium.org>
---

v2:
 - Use uclass_first_device_err instead of explicit null checking


 lib/tpm.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/tpm.c b/lib/tpm.c
index f428d45..88f2406 100644
--- a/lib/tpm.c
+++ b/lib/tpm.c
@@ -242,7 +242,7 @@ static uint32_t tpm_sendrecv_command(const void *command,
 		response_length = sizeof(response_buffer);
 	}

-	ret = uclass_first_device(UCLASS_TPM, &dev);
+	ret = uclass_first_device_err(UCLASS_TPM, &dev);
 	if (ret)
 		return ret;
 	err = tpm_xfer(dev, command, tpm_command_size(command),
@@ -261,8 +261,8 @@ int tpm_init(void)
 	int err;
 	struct udevice *dev;

-	err = uclass_first_device(UCLASS_TPM, &dev);
-	if (err || !dev)
+	err = uclass_first_device_err(UCLASS_TPM, &dev);
+	if (err)
 		return err;
 	return tpm_open(dev);
 }
--
2.7.0.GIT