inotify: race use after free/double free in inotify inode marks

[linux-beck.git] / fs / notify / inotify / inotify_user.c

diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index 472cdf29ef82598586a52f32c405bc43a8ab6b26..e46ca685b9be39fc5f1f59ae5d6c6309d60aa644 100644 (file)
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -546,21 +546,24 @@ retry:
        if (unlikely(!idr_pre_get(&group->inotify_data.idr, GFP_KERNEL)))
                goto out_err;
 
+       /* we are putting the mark on the idr, take a reference */
+       fsnotify_get_mark(&tmp_ientry->fsn_entry);
+
        spin_lock(&group->inotify_data.idr_lock);
        ret = idr_get_new_above(&group->inotify_data.idr, &tmp_ientry->fsn_entry,
                                group->inotify_data.last_wd+1,
                                &tmp_ientry->wd);
        spin_unlock(&group->inotify_data.idr_lock);
        if (ret) {
+               /* we didn't get on the idr, drop the idr reference */
+               fsnotify_put_mark(&tmp_ientry->fsn_entry);
+
                /* idr was out of memory allocate and try again */
                if (ret == -EAGAIN)
                        goto retry;
                goto out_err;
        }
 
-       /* we put the mark on the idr, take a reference */
-       fsnotify_get_mark(&tmp_ientry->fsn_entry);
-
        /* we are on the idr, now get on the inode */
        ret = fsnotify_add_mark(&tmp_ientry->fsn_entry, group, inode);
        if (ret) {
@@ -578,16 +581,13 @@ retry:
        /* return the watch descriptor for this new entry */
        ret = tmp_ientry->wd;
 
-       /* match the ref from fsnotify_init_markentry() */
-       fsnotify_put_mark(&tmp_ientry->fsn_entry);
-
        /* if this mark added a new event update the group mask */
        if (mask & ~group->mask)
                fsnotify_recalc_group_mask(group);
 
 out_err:
-       if (ret < 0)
-               kmem_cache_free(inotify_inode_mark_cachep, tmp_ientry);
+       /* match the ref from fsnotify_init_markentry() */
+       fsnotify_put_mark(&tmp_ientry->fsn_entry);
 
        return ret;
 }