tpm/tpm_ppi: Do not compare strcmp(a,b) == -1

commit 747d35bd9bb4ae6bd74b19baa5bbe32f3e0cee11 upstream.

Depending on the implementation strcmp might return the difference between
two strings not only -1,0,1 consequently
 if (strcmp (a,b) == -1)
might lead to taking the wrong branch

-> compare with < 0  instead,
which in any case is more canonical.

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/char/tpm/tpm_ppi.c b/drivers/char/tpm/tpm_ppi.c
index e1f3337..2db4419 100644 (file)
--- a/drivers/char/tpm/tpm_ppi.c
+++ b/drivers/char/tpm/tpm_ppi.c
@@ -172,7 +172,7 @@ static ssize_t tpm_store_ppi_request(struct device *dev,
         * is updated with function index from SUBREQ to SUBREQ2 since PPI
         * version 1.1
         */
-       if (strcmp(version, "1.1") == -1)
+       if (strcmp(version, "1.1") < 0)
                params[2].integer.value = TPM_PPI_FN_SUBREQ;
        else
                params[2].integer.value = TPM_PPI_FN_SUBREQ2;
@@ -182,7 +182,7 @@ static ssize_t tpm_store_ppi_request(struct device *dev,
         * string/package type. For PPI version 1.0 and 1.1, use buffer type
         * for compatibility, and use package type since 1.2 according to spec.
         */
-       if (strcmp(version, "1.2") == -1) {
+       if (strcmp(version, "1.2") < 0) {
                params[3].type = ACPI_TYPE_BUFFER;
                params[3].buffer.length = sizeof(req);
                sscanf(buf, "%d", &req);
@@ -248,7 +248,7 @@ static ssize_t tpm_show_ppi_transition_action(struct device *dev,
         * (e.g. Capella with PPI 1.0) need integer/string/buffer type, so for
         * compatibility, define params[3].type as buffer, if PPI version < 1.2
         */
-       if (strcmp(version, "1.2") == -1) {
+       if (strcmp(version, "1.2") < 0) {
                params[3].type = ACPI_TYPE_BUFFER;
                params[3].buffer.length =  0;
                params[3].buffer.pointer = NULL;
@@ -390,7 +390,7 @@ static ssize_t show_ppi_operations(char *buf, u32 start, u32 end)
        kfree(output.pointer);
        output.length = ACPI_ALLOCATE_BUFFER;
        output.pointer = NULL;
-       if (strcmp(version, "1.2") == -1)
+       if (strcmp(version, "1.2") < 0)
                return -EPERM;
 
        params[2].integer.value = TPM_PPI_FN_GETOPR;