[PATCH 2/9] sandbox: tpm: Tidy up reading and writing of device state

[Simon Glass]

At present this code assumes that the TPM data has been read but this may
not be the case. Refactor the code to use a separate pointer so we know
the current state of the data.

Add error checking for the data size.

Signed-off-by: Simon Glass <s...@chromium.org>
---

 drivers/tpm/tpm_tis_sandbox.c | 35 ++++++++++++++++++++++++-----------
 1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/drivers/tpm/tpm_tis_sandbox.c b/drivers/tpm/tpm_tis_sandbox.c
index 294d98da606..f22ed846f0a 100644
--- a/drivers/tpm/tpm_tis_sandbox.c
+++ b/drivers/tpm/tpm_tis_sandbox.c
@@ -20,7 +20,7 @@
 static struct tpm_state {
        bool valid;
        struct nvdata_state nvdata[NV_SEQ_COUNT];
-} g_state;
+} s_state, *g_state;
 
 /**
  * sandbox_tpm_read_state() - read the sandbox EC state from the state file
@@ -33,6 +33,7 @@ static struct tpm_state {
  */
 static int sandbox_tpm_read_state(const void *blob, int node)
 {
+       struct tpm_state *state = &s_state;
        const char *prop;
        int len;
        int i;
@@ -41,22 +42,27 @@ static int sandbox_tpm_read_state(const void *blob, int 
node)
                return 0;
 
        for (i = 0; i < NV_SEQ_COUNT; i++) {
+               struct nvdata_state *nvd = &state->nvdata[i];
                char prop_name[20];
 
                sprintf(prop_name, "nvdata%d", i);
                prop = fdt_getprop(blob, node, prop_name, &len);
-               if (prop && len == NV_DATA_SIZE) {
-                       memcpy(g_state.nvdata[i].data, prop, NV_DATA_SIZE);
-                       g_state.nvdata[i].present = true;
+               if (len >= NV_DATA_SIZE)
+                       return log_msg_ret("nvd", -E2BIG);
+               if (prop) {
+                       memcpy(nvd->data, prop, len);
+                       nvd->length = len;
+                       nvd->present = true;
                }
        }
-       g_state.valid = true;
+
+       s_state.valid = true;
 
        return 0;
 }
 
 /**
- * cros_ec_write_state() - Write out our state to the state file
+ * sandbox_tpm_write_state() - Write out our state to the state file
  *
  * The caller will ensure that there is a node ready for the state. The node
  * may already contain the old state, in which case it is overridden.
@@ -66,20 +72,25 @@ static int sandbox_tpm_read_state(const void *blob, int 
node)
  */
 static int sandbox_tpm_write_state(void *blob, int node)
 {
+       const struct tpm_state *state = g_state;
        int i;
 
+       if (!state)
+               return 0;
+
        /*
         * We are guaranteed enough space to write basic properties.
         * We could use fdt_add_subnode() to put each set of data in its
         * own node - perhaps useful if we add access informaiton to each.
         */
        for (i = 0; i < NV_SEQ_COUNT; i++) {
+               const struct nvdata_state *nvd = &state->nvdata[i];
                char prop_name[20];
 
-               if (g_state.nvdata[i].present) {
-                       sprintf(prop_name, "nvdata%d", i);
-                       fdt_setprop(blob, node, prop_name,
-                                   g_state.nvdata[i].data, NV_DATA_SIZE);
+               if (nvd->present) {
+                       snprintf(prop_name, sizeof(prop_name), "nvdata%d", i);
+                       fdt_setprop(blob, node, prop_name, nvd->data,
+                                   nvd->length);
                }
        }
 
@@ -233,7 +244,9 @@ static int sandbox_tpm_probe(struct udevice *dev)
 {
        struct tpm_state *tpm = dev_get_priv(dev);
 
-       memcpy(tpm, &g_state, sizeof(*tpm));
+       if (s_state.valid)
+               memcpy(tpm, &s_state, sizeof(*tpm));
+       g_state = tpm;
 
        return 0;
 }
-- 
2.32.0.93.g670b81a890-goog