tpm/tpm_ppi: Check return value of acpi_get_name

If
 status = acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
fails for whatever reason and does not return AE_OK
 if (strstr(buffer.pointer, context) != NULL) {
does dereference a null pointer.

-> Check the return value and return the status to the caller

Found by coverity
Cc: stable@vger.kernel.org
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/char/tpm/tpm_ppi.c b/drivers/char/tpm/tpm_ppi.c
index 18c5810b646..6ac9d275b73 100644
--- a/drivers/char/tpm/tpm_ppi.c
+++ b/drivers/char/tpm/tpm_ppi.c
@@ -30,6 +30,9 @@ static acpi_status ppi_callback(acpi_handle handle, u32 level, void *context,
 	acpi_status status;
 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 	status = acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
+	if (ACPI_FAILURE(status))
+		return status;
+
 	if (strstr(buffer.pointer, context) != NULL) {
 		*return_value = handle;
 		kfree(buffer.pointer);