tpm_tis: Explicitly check for error code

JIRA: https://issues.redhat.com/browse/RHEL-72765

Upstream Status: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

Conflicts: Missing line due to missing f25534a.

commit 513253f
Author: Alexander Steffen <[email protected]>
Date:   Tue Jun 13 20:02:56 2023 +0200

    tpm_tis: Explicitly check for error code

    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: [email protected]
    Fixes: cb53542 ("[PATCH] tpm: spacing cleanups 2")
    Signed-off-by: Alexander Steffen <[email protected]>
    Reviewed-by: Jarkko Sakkinen <[email protected]>
    Signed-off-by: Jarkko Sakkinen <[email protected]>

Signed-off-by: Štěpán Horáček <[email protected]>

Author: shoracek

drivers/char/tpm/tpm_tis_core.c

@@ -343,6 +343,7 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
 	int size = 0;
 	int status;
 	u32 expected;
+	int rc;
 
 	if (count < TPM_HEADER_SIZE) {
 		size = -EIO;
@@ -362,8 +363,13 @@ 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;