ext4: fix a race which could leak memory in ext4_groupinfo_create_slab()

In ext4_groupinfo_create_slab, we create ext4_groupinfo_caches within
ext4_grpinfo_slab_create_mutex, but set it outside the lock, and there
does exist some case that we may create it twice and causes a memory
leak.  So set it before we call mutex_unlock.

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 04a3d92..2b9a71b 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2404,14 +2404,14 @@ static int ext4_groupinfo_create_slab(size_t size)
                                        slab_size, 0, SLAB_RECLAIM_ACCOUNT,
                                        NULL);
 
+       ext4_groupinfo_caches[cache_index] = cachep;
+
        mutex_unlock(&ext4_grpinfo_slab_create_mutex);
        if (!cachep) {
                printk(KERN_EMERG "EXT4: no memory for groupinfo slab cache\n");
                return -ENOMEM;
        }
 
-       ext4_groupinfo_caches[cache_index] = cachep;
-
        return 0;
 }