Re: [PATCH 1/4] remoteproc: Use fixed length field for firmware name

[Matt Redfearn]

Hi Loic,


On 13/10/16 14:22, loic pallardy wrote:

On 10/11/2016 03:39 PM, Matt Redfearn wrote:

Storage of the firmware name was inconsistent, either storing a pointer
to a name stored with unknown ownership, or a variable length tacked
onto the end of the struct proc allocated in rproc_alloc.

In preparation for allowing the firmware of an already allocated struct
rproc to be changed, the easiest way to allow reallocation of the name
is to switch to a fixed length buffer held as part of the struct rproc.
That way we can either copy the provided firmware name into it, or print
into it based on a name template. A new function,
rproc_set_firmware_name() is introduced for this purpose, and that logic
removed from rproc_alloc().

Signed-off-by: Matt Redfearn <matt.redfe...@imgtec.com>
---

drivers/remoteproc/remoteproc_core.c | 64 +++++++++++++++++++++++-------------

 include/linux/remoteproc.h           |  4 ++-
 2 files changed, 45 insertions(+), 23 deletions(-)

diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c

index fe0539ed9cb5..48cd9d5afb69 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c

@@ -1309,6 +1309,42 @@ static void rproc_type_release(struct device *dev)

     kfree(rproc);
 }

+/**
+ * rproc_set_firmware_name() - helper to create a valid firmare name
+ * @rproc: remote processor
+ * @firmware: name of firmware file, can be NULL
+ *

+ * If the caller didn't pass in a firmware name then construct a default name, + * otherwise the provided name is copied into the firmware field of struct

+ * rproc. If the name is too long to fit, -EINVAL is returned.
+ *
+ * Returns 0 on success and an appropriate error code otherwise.
+ */

+static int rproc_set_firmware_name(struct rproc *rproc, const char *firmware)

+{
+    char *cp, *template = "rproc-%s-fw";
+    int name_len;
+
+    if (firmware) {
+        name_len = strlen(firmware);
+        cp = memchr(firmware, '\n', name_len);
+        if (cp)
+            name_len = cp - firmware;
+
+        if (name_len > RPROC_MAX_FIRMWARE_NAME_LEN)

Hi Matt,

As you are added '\0' at offset name_len, name_len should be < to RPROC_MAX_FIRMWARE_NAME_LEN.

Test should be if (name_len >= RPROC_MAX_FIRMWARE_NAME_LEN)

Yes - good spot, thanks :-)

Matt

Regards,
Loic

+            return -EINVAL;
+
+        strncpy(rproc->firmware, firmware, name_len);
+        rproc->firmware[name_len] = '\0';
+    } else {
+        snprintf(rproc->firmware, RPROC_MAX_FIRMWARE_NAME_LEN,
+             template, rproc->name);
+    }
+
+    dev_dbg(&rproc->dev, "Using firmware %s\n", rproc->firmware);
+    return 0;
+}
+
 static struct device_type rproc_type = {
     .name        = "remoteproc",
     .release    = rproc_type_release,

@@ -1342,35 +1378,14 @@ struct rproc *rproc_alloc(struct device *dev, const char *name,

                 const char *firmware, int len)
 {
     struct rproc *rproc;
-    char *p, *template = "rproc-%s-fw";
-    int name_len = 0;

     if (!dev || !name || !ops)
         return NULL;

-    if (!firmware)
-        /*
-         * Make room for default firmware name (minus %s plus '\0').
-         * If the caller didn't pass in a firmware name then
-         * construct a default name.  We're already glomming 'len'
-         * bytes onto the end of the struct rproc allocation, so do
-         * a few more for the default firmware name (but only if
-         * the caller doesn't pass one).
-         */
-        name_len = strlen(name) + strlen(template) - 2 + 1;
-
-    rproc = kzalloc(sizeof(struct rproc) + len + name_len, GFP_KERNEL);
+    rproc = kzalloc(sizeof(struct rproc) + len, GFP_KERNEL);
     if (!rproc)
         return NULL;

-    if (!firmware) {
-        p = (char *)rproc + sizeof(struct rproc) + len;
-        snprintf(p, name_len, template, name);
-    } else {
-        p = (char *)firmware;
-    }
-
-    rproc->firmware = p;
     rproc->name = name;
     rproc->ops = ops;
     rproc->priv = &rproc[1];

@@ -1389,6 +1404,11 @@ struct rproc *rproc_alloc(struct device *dev, const char *name,

     dev_set_name(&rproc->dev, "remoteproc%d", rproc->index);

+    if (rproc_set_firmware_name(rproc, firmware)) {
+        put_device(&rproc->dev);
+        return NULL;
+    }
+
     atomic_set(&rproc->power, 0);

     /* Set ELF as the default fw_ops handler */
diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
index 1c457a8dd5a6..7a6f9ad55011 100644
--- a/include/linux/remoteproc.h
+++ b/include/linux/remoteproc.h
@@ -42,6 +42,8 @@
 #include <linux/idr.h>
 #include <linux/of.h>

+#define RPROC_MAX_FIRMWARE_NAME_LEN 128
+
 /**
  * struct resource_table - firmware resource table header
  * @ver: version number
@@ -416,7 +418,7 @@ struct rproc {
     struct list_head node;
     struct iommu_domain *domain;
     const char *name;
-    const char *firmware;
+    char firmware[RPROC_MAX_FIRMWARE_NAME_LEN];
     void *priv;
     const struct rproc_ops *ops;
     struct device dev;