tpm_tis: Explicitly check for error code

commit 513253f8c293c0c8bd46d09d337fc892bf8f9f48 upstream.

recv_data either returns the number of received bytes, or a negative value
representing an error code. Adding the return value directly to the total
number of received bytes therefore looks a little weird, since it might add
a negative error code to a sum of bytes.

The following check for size < expected usually makes the function return
ETIME in that case, so it does not cause too many problems in practice. But
to make the code look cleaner and because the caller might still be
interested in the original error code, explicitly check for the presence of
an error code and pass that through.

Cc: stable@vger.kernel.org
Fixes: cb5354253af2 ("[PATCH] tpm: spacing cleanups 2")
Signed-off-by: Alexander Steffen <Alexander.Steffen@infineon.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 55f6ff1e05aa..44f71f2c8cfa 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -356,8 +356,13 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
 		goto out;
 	}
 
-	size += recv_data(chip, &buf[TPM_HEADER_SIZE],
-			  expected - TPM_HEADER_SIZE);
+	rc = recv_data(chip, &buf[TPM_HEADER_SIZE],
+		       expected - TPM_HEADER_SIZE);
+	if (rc < 0) {
+		size = rc;
+		goto out;
+	}
+	size += rc;
 	if (size < expected) {
 		dev_err(&chip->dev, "Unable to read remainder of result\n");
 		size = -ETIME;