Driver core: change add_uevent_var to use a struct

This changes the uevent buffer functions to use a struct instead of a
long list of parameters. It does no longer require the caller to do the
proper buffer termination and size accounting, which is currently wrong
in some places. It fixes a known bug where parts of the uevent
environment are overwritten because of wrong index calculations.

Many thanks to Mathieu Desnoyers for finding bugs and improving the
error handling.

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 25 insertions, 59 deletions

diff --git a/drivers/base/core.c b/drivers/base/core.c
index ec86d6fc2360..d487c032dc4a 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -141,33 +141,23 @@ static const char *dev_uevent_name(struct kset *kset, struct kobject *kobj)
         return NULL;
 }
 
-static int dev_uevent(struct kset *kset, struct kobject *kobj, char **envp,
-                        int num_envp, char *buffer, int buffer_size)
+static int dev_uevent(struct kset *kset, struct kobject *kobj,
+                      struct kobj_uevent_env *env)
 {
         struct device *dev = to_dev(kobj);
-        int i = 0;
-        int length = 0;
         int retval = 0;
 
         /* add the major/minor if present */
         if (MAJOR(dev->devt)) {
-                add_uevent_var(envp, num_envp, &i,
-                               buffer, buffer_size, &length,
-                               "MAJOR=%u", MAJOR(dev->devt));
-                add_uevent_var(envp, num_envp, &i,
-                               buffer, buffer_size, &length,
-                               "MINOR=%u", MINOR(dev->devt));
+                add_uevent_var(env, "MAJOR=%u", MAJOR(dev->devt));
+                add_uevent_var(env, "MINOR=%u", MINOR(dev->devt));
         }
 
         if (dev->type && dev->type->name)
-                add_uevent_var(envp, num_envp, &i,
-                               buffer, buffer_size, &length,
-                               "DEVTYPE=%s", dev->type->name);
+                add_uevent_var(env, "DEVTYPE=%s", dev->type->name);
 
         if (dev->driver)
-                add_uevent_var(envp, num_envp, &i,
-                               buffer, buffer_size, &length,
-                               "DRIVER=%s", dev->driver->name);
+                add_uevent_var(env, "DRIVER=%s", dev->driver->name);
 
 #ifdef CONFIG_SYSFS_DEPRECATED
         if (dev->class) {
@@ -181,59 +171,43 @@ static int dev_uevent(struct kset *kset, struct kobject *kobj, char **envp,
 
                         path = kobject_get_path(&parent->kobj, GFP_KERNEL);
                         if (path) {
-                                add_uevent_var(envp, num_envp, &i,
-                                               buffer, buffer_size, &length,
-                                               "PHYSDEVPATH=%s", path);
+                                add_uevent_var(env, "PHYSDEVPATH=%s", path);
                                 kfree(path);
                         }
 
-                        add_uevent_var(envp, num_envp, &i,
-                                       buffer, buffer_size, &length,
-                                       "PHYSDEVBUS=%s", parent->bus->name);
+                        add_uevent_var(env, "PHYSDEVBUS=%s", parent->bus->name);
 
                         if (parent->driver)
-                                add_uevent_var(envp, num_envp, &i,
-                                               buffer, buffer_size, &length,
-                                               "PHYSDEVDRIVER=%s", parent->driver->name);
+                                add_uevent_var(env, "PHYSDEVDRIVER=%s",
+                                               parent->driver->name);
                 }
         } else if (dev->bus) {
-                add_uevent_var(envp, num_envp, &i,
-                               buffer, buffer_size, &length,
-                               "PHYSDEVBUS=%s", dev->bus->name);
+                add_uevent_var(env, "PHYSDEVBUS=%s", dev->bus->name);
 
                 if (dev->driver)
-                        add_uevent_var(envp, num_envp, &i,
-                                       buffer, buffer_size, &length,
-                                       "PHYSDEVDRIVER=%s", dev->driver->name);
+                        add_uevent_var(env, "PHYSDEVDRIVER=%s", dev->driver->name);
         }
 #endif
 
-        /* terminate, set to next free slot, shrink available space */
-        envp[i] = NULL;
-        envp = &envp[i];
-        num_envp -= i;
-        buffer = &buffer[length];
-        buffer_size -= length;
-
+        /* have the bus specific function add its stuff */
         if (dev->bus && dev->bus->uevent) {
-                /* have the bus specific function add its stuff */
-                retval = dev->bus->uevent(dev, envp, num_envp, buffer, buffer_size);
+                retval = dev->bus->uevent(dev, env);
                 if (retval)
                         pr_debug ("%s: bus uevent() returned %d\n",
                                   __FUNCTION__, retval);
         }
 
+        /* have the class specific function add its stuff */
         if (dev->class && dev->class->dev_uevent) {
-                /* have the class specific function add its stuff */
-                retval = dev->class->dev_uevent(dev, envp, num_envp, buffer, buffer_size);
+                retval = dev->class->dev_uevent(dev, env);
                 if (retval)
                         pr_debug("%s: class uevent() returned %d\n",
                                  __FUNCTION__, retval);
         }
 
+        /* have the device type specific fuction add its stuff */
         if (dev->type && dev->type->uevent) {
-                /* have the device type specific fuction add its stuff */
-                retval = dev->type->uevent(dev, envp, num_envp, buffer, buffer_size);
+                retval = dev->type->uevent(dev, env);
                 if (retval)
                         pr_debug("%s: dev_type uevent() returned %d\n",
                                  __FUNCTION__, retval);
@@ -253,9 +227,7 @@ static ssize_t show_uevent(struct device *dev, struct device_attribute *attr,
 {
         struct kobject *top_kobj;
         struct kset *kset;
-        char *envp[32];
-        char *data = NULL;
-        char *pos;
+        struct kobj_uevent_env *env = NULL;
         int i;
         size_t count = 0;
         int retval;
@@ -278,26 +250,20 @@ static ssize_t show_uevent(struct device *dev, struct device_attribute *attr,
                 if (!kset->uevent_ops->filter(kset, &dev->kobj))
                         goto out;
 
-        data = (char *)get_zeroed_page(GFP_KERNEL);
-        if (!data)
+        env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
+        if (!env)
                 return -ENOMEM;
 
         /* let the kset specific function add its keys */
-        pos = data;
-        memset(envp, 0, sizeof(envp));
-        retval = kset->uevent_ops->uevent(kset, &dev->kobj,
-                                          envp, ARRAY_SIZE(envp),
-                                          pos, PAGE_SIZE);
+        retval = kset->uevent_ops->uevent(kset, &dev->kobj, env);
         if (retval)
                 goto out;
 
         /* copy keys to file */
-        for (i = 0; envp[i]; i++) {
-                pos = &buf[count];
-                count += sprintf(pos, "%s\n", envp[i]);
-        }
+        for (i = 0; i < env->envp_idx; i++)
+                count += sprintf(&buf[count], "%s\n", env->envp[i]);
 out:
-        free_page((unsigned long)data);
+        kfree(env);
         return count;
 }