firmware, memmap: fix firmware_map_entry leak

Yasuaki Ishimatsu · torvalds · commit 7a6f93b0a873 · 2013-04-29T15:54:38.000-07:00
When hot removing memory, a firmware_map_entry which has memory range of
the memory is released by release_firmware_map_entry().  If the entry is
allocated by bootmem, release_firmware_map_entry() adds the entry to
map_entires_bootmem list when firmware_map_find_entry() finds the entry
from map_entries list.  But firmware_map_find_entry never find the entry
sicne map_entires list does not have the entry.  So the entry just
leaks.

Here are steps of leaking firmware_map_entry:
firmware_map_remove()
-&gt; firmware_map_find_entry()
   Find released entry from map_entries list
-&gt; firmware_map_remove_entry()
   Delete the entry from map_entries list
-&gt; remove_sysfs_fw_map_entry()
   ...
   -&gt; release_firmware_map_entry()
      -&gt; firmware_map_find_entry()
         Find the entry from map_entries list but the entry has been
         deleted from map_entries list. So the entry is not added
         to map_entries_bootmem. Thus the entry leaks

release_firmware_map_entry() should not call firmware_map_find_entry()
since releaed entry has been deleted from map_entries list.  So the
patch delete firmware_map_find_entry() from releae_firmware_map_entry()

Signed-off-by: Yasuaki Ishimatsu &lt;isimatu.yasuaki@jp.fujitsu.com&gt;
Reviewed-by: Wanpeng Li &lt;liwanp@linux.vnet.ibm.com&gt;
Reviewed-by: Tang Chen &lt;tangchen@cn.fujitsu.com&gt;
Acked-by: Toshi Kani &lt;toshi.kani@hp.com&gt;
Cc: Wen Congyang &lt;wency@cn.fujitsu.com&gt;
Cc: Greg KH &lt;greg@kroah.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
diff --git a/drivers/firmware/memmap.c b/drivers/firmware/memmap.c
@@ -114,12 +114,9 @@ static void __meminit release_firmware_map_entry(struct kobject *kobj)
 		 * map_entries_bootmem here, and deleted from &map_entries in
 		 * firmware_map_remove_entry().
 		 */
-		if (firmware_map_find_entry(entry->start, entry->end,
-		    entry->type)) {
-			spin_lock(&map_entries_bootmem_lock);
-			list_add(&entry->list, &map_entries_bootmem);
-			spin_unlock(&map_entries_bootmem_lock);
-		}
+		spin_lock(&map_entries_bootmem_lock);
+		list_add(&entry->list, &map_entries_bootmem);
+		spin_unlock(&map_entries_bootmem_lock);
 
 		return;
 	}
