[PATCH] powerpc: Cope with duplicate node & property names in /proc/device-tree

Various dodgy firmware might give us nodes and/or properties in the device
tree with conflicting names. That's generally ok, except for when we export
the device tree via /proc, so check when we're creating the proc device tree
and munge names accordingly.

Tested on a faked device tree with kexec, would be good if someone with
actual bogus firmware could try it, but just for completeness.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 80 insertions, 23 deletions

diff --git a/fs/proc/proc_devtree.c b/fs/proc/proc_devtree.c
index 596b4b4f1cc8..abdf068bc27f 100644
--- a/fs/proc/proc_devtree.c
+++ b/fs/proc/proc_devtree.c
@@ -52,7 +52,8 @@ static int property_read_proc(char *page, char **start, off_t off,
  * Add a property to a node
  */
 static struct proc_dir_entry *
-__proc_device_tree_add_prop(struct proc_dir_entry *de, struct property *pp)
+__proc_device_tree_add_prop(struct proc_dir_entry *de, struct property *pp,
+                const char *name)
 {
         struct proc_dir_entry *ent;
 
@@ -60,14 +61,14 @@ __proc_device_tree_add_prop(struct proc_dir_entry *de, struct property *pp)
          * Unfortunately proc_register puts each new entry
          * at the beginning of the list.  So we rearrange them.
          */
-        ent = create_proc_read_entry(pp->name,
-                                     strncmp(pp->name, "security-", 9)
+        ent = create_proc_read_entry(name,
+                                     strncmp(name, "security-", 9)
                                      ? S_IRUGO : S_IRUSR, de,
                                      property_read_proc, pp);
         if (ent == NULL)
                 return NULL;
 
-        if (!strncmp(pp->name, "security-", 9))
+        if (!strncmp(name, "security-", 9))
                 ent->size = 0; /* don't leak number of password chars */
         else
                 ent->size = pp->length;
@@ -78,7 +79,7 @@ __proc_device_tree_add_prop(struct proc_dir_entry *de, struct property *pp)
 
 void proc_device_tree_add_prop(struct proc_dir_entry *pde, struct property *prop)
 {
-        __proc_device_tree_add_prop(pde, prop);
+        __proc_device_tree_add_prop(pde, prop, prop->name);
 }
 
 void proc_device_tree_remove_prop(struct proc_dir_entry *pde,
@@ -106,6 +107,69 @@ void proc_device_tree_update_prop(struct proc_dir_entry *pde,
 }
 
 /*
+ * Various dodgy firmware might give us nodes and/or properties with
+ * conflicting names. That's generally ok, except for exporting via /proc,
+ * so munge names here to ensure they're unique.
+ */
+
+static int duplicate_name(struct proc_dir_entry *de, const char *name)
+{
+        struct proc_dir_entry *ent;
+        int found = 0;
+
+        spin_lock(&proc_subdir_lock);
+
+        for (ent = de->subdir; ent != NULL; ent = ent->next) {
+                if (strcmp(ent->name, name) == 0) {
+                        found = 1;
+                        break;
+                }
+        }
+
+        spin_unlock(&proc_subdir_lock);
+
+        return found;
+}
+
+static const char *fixup_name(struct device_node *np, struct proc_dir_entry *de,
+                const char *name)
+{
+        char *fixed_name;
+        int fixup_len = strlen(name) + 2 + 1; /* name + #x + \0 */
+        int i = 1, size;
+
+realloc:
+        fixed_name = kmalloc(fixup_len, GFP_KERNEL);
+        if (fixed_name == NULL) {
+                printk(KERN_ERR "device-tree: Out of memory trying to fixup "
+                                "name \"%s\"\n", name);
+                return name;
+        }
+
+retry:
+        size = snprintf(fixed_name, fixup_len, "%s#%d", name, i);
+        size++; /* account for NULL */
+
+        if (size > fixup_len) {
+                /* We ran out of space, free and reallocate. */
+                kfree(fixed_name);
+                fixup_len = size;
+                goto realloc;
+        }
+
+        if (duplicate_name(de, fixed_name)) {
+                /* Multiple duplicates. Retry with a different offset. */
+                i++;
+                goto retry;
+        }
+
+        printk(KERN_WARNING "device-tree: Duplicate name in %s, "
+                        "renamed to \"%s\"\n", np->full_name, fixed_name);
+
+        return fixed_name;
+}
+
+/*
  * Process a node, adding entries for its children and its properties.
  */
 void proc_device_tree_add_node(struct device_node *np,
@@ -118,37 +182,30 @@ void proc_device_tree_add_node(struct device_node *np,
 
         set_node_proc_entry(np, de);
         for (child = NULL; (child = of_get_next_child(np, child));) {
+                /* Use everything after the last slash, or the full name */
                 p = strrchr(child->full_name, '/');
                 if (!p)
                         p = child->full_name;
                 else
                         ++p;
+
+                if (duplicate_name(de, p))
+                        p = fixup_name(np, de, p);
+
                 ent = proc_mkdir(p, de);
                 if (ent == 0)
                         break;
                 proc_device_tree_add_node(child, ent);
         }
         of_node_put(child);
+
         for (pp = np->properties; pp != 0; pp = pp->next) {
-                /*
-                 * Yet another Apple device-tree bogosity: on some machines,
-                 * they have properties & nodes with the same name. Those
-                 * properties are quite unimportant for us though, thus we
-                 * simply "skip" them here, but we do have to check.
-                 */
-                spin_lock(&proc_subdir_lock);
-                for (ent = de->subdir; ent != NULL; ent = ent->next)
-                        if (!strcmp(ent->name, pp->name))
-                                break;
-                spin_unlock(&proc_subdir_lock);
-                if (ent != NULL) {
-                        printk(KERN_WARNING "device-tree: property \"%s\" name"
-                               " conflicts with node in %s\n", pp->name,
-                               np->full_name);
-                        continue;
-                }
+                p = pp->name;
+
+                if (duplicate_name(de, p))
+                        p = fixup_name(np, de, p);
 
-                ent = __proc_device_tree_add_prop(de, pp);
+                ent = __proc_device_tree_add_prop(de, pp, p);
                 if (ent == 0)
                         break;
         }