tpm: sandbox: fix wrong assignment with a simplification

The recv variable in sandbox_tpm2_fill_buf() is a pointer on a pointer
of a char array. It means accessing *recv is the char array pointer
itself while **recv is the first character of that array. There is no
need for such indirection here, so simplify the code.

Simplifying things will make the last assignment right: "*recv = NULL"
is now correct. The issue has been found by the following Coverity
Scan report:

    CID 183371:  Incorrect expression  (UNUSED_VALUE)
    Assigning value "4UL" to "*recv" here, but that stored value is overwritten before it can be used.
    232             *recv += sizeof(rc);
    233
    234             /* Add trailing \0 */
    235             *recv = NULL;

While at simplifying things, use '\0' instead of NULL when adding an
empty char at the end of the buffer.

Reported-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

diff --git a/drivers/tpm/tpm2_tis_sandbox.c b/drivers/tpm/tpm2_tis_sandbox.c
index b15ec73..f282ea6 100644 (file)
--- a/drivers/tpm/tpm2_tis_sandbox.c
+++ b/drivers/tpm/tpm2_tis_sandbox.c
@@ -215,24 +215,24 @@ static int sandbox_tpm2_check_readyness(struct udevice *dev, int command)
        return 0;
 }
 
-static int sandbox_tpm2_fill_buf(u8 **recv, size_t *recv_len, u16 tag, u32 rc)
+static int sandbox_tpm2_fill_buf(u8 *recv, size_t *recv_len, u16 tag, u32 rc)
 {
        *recv_len = sizeof(tag) + sizeof(u32) + sizeof(rc);
 
        /* Write tag */
-       put_unaligned_be16(tag, *recv);
-       *recv += sizeof(tag);
+       put_unaligned_be16(tag, recv);
+       recv += sizeof(tag);
 
        /* Write length */
-       put_unaligned_be32(*recv_len, *recv);
-       *recv += sizeof(u32);
+       put_unaligned_be32(*recv_len, recv);
+       recv += sizeof(u32);
 
        /* Write return code */
-       put_unaligned_be32(rc, *recv);
-       *recv += sizeof(rc);
+       put_unaligned_be32(rc, recv);
+       recv += sizeof(rc);
 
        /* Add trailing \0 */
-       *recv = NULL;
+       *recv = '\0';
 
        return 0;
 }
@@ -287,7 +287,7 @@ static int sandbox_tpm2_xfer(struct udevice *dev, const u8 *sendbuf,
                printf("TPM2: Unmatching length, received: %ld, expected: %d\n",
                       send_size, length);
                rc = TPM2_RC_SIZE;
-               sandbox_tpm2_fill_buf(&recv, recv_len, tag, rc);
+               sandbox_tpm2_fill_buf(recv, recv_len, tag, rc);
                return 0;
        }
 
@@ -295,13 +295,13 @@ static int sandbox_tpm2_xfer(struct udevice *dev, const u8 *sendbuf,
        sent += sizeof(command);
        rc = sandbox_tpm2_check_readyness(dev, command);
        if (rc) {
-               sandbox_tpm2_fill_buf(&recv, recv_len, tag, rc);
+               sandbox_tpm2_fill_buf(recv, recv_len, tag, rc);
                return 0;
        }
 
        rc = sandbox_tpm2_check_session(dev, command, tag, &sent, &hierarchy);
        if (rc) {
-               sandbox_tpm2_fill_buf(&recv, recv_len, tag, rc);
+               sandbox_tpm2_fill_buf(recv, recv_len, tag, rc);
                return 0;
        }
 
@@ -319,7 +319,7 @@ static int sandbox_tpm2_xfer(struct udevice *dev, const u8 *sendbuf,
 
                tpm->startup_done = true;
 
-               sandbox_tpm2_fill_buf(&recv, recv_len, tag, rc);
+               sandbox_tpm2_fill_buf(recv, recv_len, tag, rc);
                break;
 
        case TPM2_CC_SELF_TEST:
@@ -335,7 +335,7 @@ static int sandbox_tpm2_xfer(struct udevice *dev, const u8 *sendbuf,
 
                tpm->tests_done = true;
 
-               sandbox_tpm2_fill_buf(&recv, recv_len, tag, rc);
+               sandbox_tpm2_fill_buf(recv, recv_len, tag, rc);
                break;
 
        case TPM2_CC_CLEAR:
@@ -358,7 +358,7 @@ static int sandbox_tpm2_xfer(struct udevice *dev, const u8 *sendbuf,
                                tpm->pcr[i][j] = 0;
                }
 
-               sandbox_tpm2_fill_buf(&recv, recv_len, tag, rc);
+               sandbox_tpm2_fill_buf(recv, recv_len, tag, rc);
                break;
 
        case TPM2_CC_HIERCHANGEAUTH:
@@ -372,7 +372,7 @@ static int sandbox_tpm2_xfer(struct udevice *dev, const u8 *sendbuf,
                        sent += new_pw_sz;
                }
 
-               sandbox_tpm2_fill_buf(&recv, recv_len, tag, rc);
+               sandbox_tpm2_fill_buf(recv, recv_len, tag, rc);
                break;
 
        case TPM2_CC_GET_CAPABILITY:
@@ -392,7 +392,7 @@ static int sandbox_tpm2_xfer(struct udevice *dev, const u8 *sendbuf,
                if (!property_count ||
                    property + property_count > TPM2_PROPERTY_NB) {
                        rc = TPM2_RC_HANDLE;
-                       return sandbox_tpm2_fill_buf(&recv, recv_len, tag, rc);
+                       return sandbox_tpm2_fill_buf(recv, recv_len, tag, rc);
                }
 
                /* Write tag */
@@ -445,7 +445,7 @@ static int sandbox_tpm2_xfer(struct udevice *dev, const u8 *sendbuf,
                tpm->properties[TPM2_LOCKOUT_RECOVERY] = get_unaligned_be32(sent);
                sent += sizeof(*tpm->properties);
 
-               sandbox_tpm2_fill_buf(&recv, recv_len, tag, rc);
+               sandbox_tpm2_fill_buf(recv, recv_len, tag, rc);
                break;
 
        case TPM2_CC_PCR_READ:
@@ -454,7 +454,7 @@ static int sandbox_tpm2_xfer(struct udevice *dev, const u8 *sendbuf,
                if (selections != 1) {
                        printf("Sandbox cannot handle more than one PCR\n");
                        rc = TPM2_RC_VALUE;
-                       return sandbox_tpm2_fill_buf(&recv, recv_len, tag, rc);
+                       return sandbox_tpm2_fill_buf(recv, recv_len, tag, rc);
                }
 
                alg = get_unaligned_be16(sent);
@@ -462,7 +462,7 @@ static int sandbox_tpm2_xfer(struct udevice *dev, const u8 *sendbuf,
                if (alg != TPM2_ALG_SHA256) {
                        printf("Sandbox TPM only handle SHA256 algorithm\n");
                        rc = TPM2_RC_VALUE;
-                       return sandbox_tpm2_fill_buf(&recv, recv_len, tag, rc);
+                       return sandbox_tpm2_fill_buf(recv, recv_len, tag, rc);
                }
 
                pcr_array_sz = *sent;
@@ -470,7 +470,7 @@ static int sandbox_tpm2_xfer(struct udevice *dev, const u8 *sendbuf,
                if (!pcr_array_sz || pcr_array_sz > 8) {
                        printf("Sandbox TPM cannot handle so much PCRs\n");
                        rc = TPM2_RC_VALUE;
-                       return sandbox_tpm2_fill_buf(&recv, recv_len, tag, rc);
+                       return sandbox_tpm2_fill_buf(recv, recv_len, tag, rc);
                }
 
                for (i = 0; i < pcr_array_sz; i++)
@@ -480,13 +480,13 @@ static int sandbox_tpm2_xfer(struct udevice *dev, const u8 *sendbuf,
                        printf("Sandbox TPM handles up to %d PCR(s)\n",
                               SANDBOX_TPM_PCR_NB);
                        rc = TPM2_RC_VALUE;
-                       return sandbox_tpm2_fill_buf(&recv, recv_len, tag, rc);
+                       return sandbox_tpm2_fill_buf(recv, recv_len, tag, rc);
                }
 
                if (!pcr_map) {
                        printf("Empty PCR map.\n");
                        rc = TPM2_RC_VALUE;
-                       return sandbox_tpm2_fill_buf(&recv, recv_len, tag, rc);
+                       return sandbox_tpm2_fill_buf(recv, recv_len, tag, rc);
                }
 
                for (i = 0; i < SANDBOX_TPM_PCR_NB; i++)
@@ -538,7 +538,7 @@ static int sandbox_tpm2_xfer(struct udevice *dev, const u8 *sendbuf,
                if (pcr_nb != 1) {
                        printf("Sandbox cannot handle more than one PCR\n");
                        rc = TPM2_RC_VALUE;
-                       return sandbox_tpm2_fill_buf(&recv, recv_len, tag, rc);
+                       return sandbox_tpm2_fill_buf(recv, recv_len, tag, rc);
                }
 
                /* Check the hash algorithm */
@@ -547,19 +547,19 @@ static int sandbox_tpm2_xfer(struct udevice *dev, const u8 *sendbuf,
                if (alg != TPM2_ALG_SHA256) {
                        printf("Sandbox TPM only handle SHA256 algorithm\n");
                        rc = TPM2_RC_VALUE;
-                       return sandbox_tpm2_fill_buf(&recv, recv_len, tag, rc);
+                       return sandbox_tpm2_fill_buf(recv, recv_len, tag, rc);
                }
 
                /* Extend the PCR */
                rc = sandbox_tpm2_extend(dev, pcr_index, sent);
 
-               sandbox_tpm2_fill_buf(&recv, recv_len, tag, rc);
+               sandbox_tpm2_fill_buf(recv, recv_len, tag, rc);
                break;
 
        default:
                printf("TPM2 command %02x unknown in Sandbox\n", command);
                rc = TPM2_RC_COMMAND_CODE;
-               sandbox_tpm2_fill_buf(&recv, recv_len, tag, rc);
+               sandbox_tpm2_fill_buf(recv, recv_len, tag, rc);
        }
 
        return 0;