btrfs: CVE-2018-14609

btrfs: relocation: Only remove reloc rb_trees if reloc control has been initialized

References:
https://patchwork.kernel.org/patch/10500521/
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.9.y&id=93d960de56cef4582088dfc0ba9494143351772f

Signed-off-by: Andreas Wellving <andreas.wellving@enea.com>

Change-Id: Ic1390aed45c16ad0f770c1bef36e8508b66230d2

2 files changed, 70 insertions, 0 deletions

diff --git a/patches/cve/4.9.x.scc b/patches/cve/4.9.x.scc
index 75f6253..9c3d920 100644
--- a/patches/cve/4.9.x.scc
+++ b/patches/cve/4.9.x.scc
@@ -49,3 +49,6 @@ patch CVE-2018-9363-Bluetooth-hidp-buffer-overflow-in-hidp_process_repor.patch
 
 #CVEs fixed in 4.9.125:
 patch CVE-2018-10938-Cipso-cipso_v4_optptr-enter-infinite-loop.patch
+
+#CVEs fixed in 4.9.127:
+patch CVE-2018-14609-btrfs-relocation-Only-remove-reloc-rb_trees-if-reloc.patch
diff --git a/patches/cve/CVE-2018-14609-btrfs-relocation-Only-remove-reloc-rb_trees-if-reloc.patch b/patches/cve/CVE-2018-14609-btrfs-relocation-Only-remove-reloc-rb_trees-if-reloc.patch
new file mode 100644
index 0000000..8d1a8cb
--- /dev/null
+++ b/patches/cve/CVE-2018-14609-btrfs-relocation-Only-remove-reloc-rb_trees-if-reloc.patch
@@ -0,0 +1,67 @@
+From 389305b2aa68723c754f88d9dbd268a400e10664 Mon Sep 17 00:00:00 2001
+From: Qu Wenruo <wqu@suse.com>
+Date: Tue, 3 Jul 2018 17:10:07 +0800
+Subject: [PATCH] btrfs: relocation: Only remove reloc rb_trees if reloc
+ control has been initialized
+
+Invalid reloc tree can cause kernel NULL pointer dereference when btrfs
+does some cleanup of the reloc roots.
+
+It turns out that fs_info::reloc_ctl can be NULL in
+btrfs_recover_relocation() as we allocate relocation control after all
+reloc roots have been verified.
+So when we hit: note, we haven't called set_reloc_control() thus
+fs_info::reloc_ctl is still NULL.
+
+CVE: CVE-2018-14609   
+Upstream-Status: Backport  
+
+Link: https://bugzilla.kernel.org/show_bug.cgi?id=199833
+Reported-by: Xu Wen <wen.xu@gatech.edu>
+Signed-off-by: Qu Wenruo <wqu@suse.com>
+Tested-by: Gu Jinxiang <gujx@cn.fujitsu.com>
+Reviewed-by: David Sterba <dsterba@suse.com>
+Signed-off-by: David Sterba <dsterba@suse.com>
+Signed-off-by: Andreas Wellving <andreas.wellving@enea.com>
+---
+ fs/btrfs/relocation.c | 23 ++++++++++++-----------
+ 1 file changed, 12 insertions(+), 11 deletions(-)
+
+diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
+index 229f721..b98d7a5 100644
+--- a/fs/btrfs/relocation.c
++++ b/fs/btrfs/relocation.c
+@@ -1281,18 +1281,19 @@ static void __del_reloc_root(struct btrfs_root *root)
+        struct mapping_node *node = NULL;
+        struct reloc_control *rc = fs_info->reloc_ctl;
+ 
+-       spin_lock(&rc->reloc_root_tree.lock);
+-       rb_node = tree_search(&rc->reloc_root_tree.rb_root,
+-                             root->node->start);
+-       if (rb_node) {
+-               node = rb_entry(rb_node, struct mapping_node, rb_node);
+-               rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
++       if (rc) {
++               spin_lock(&rc->reloc_root_tree.lock);
++               rb_node = tree_search(&rc->reloc_root_tree.rb_root,
++                                     root->node->start);
++               if (rb_node) {
++                       node = rb_entry(rb_node, struct mapping_node, rb_node);
++                       rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
++               }
++               spin_unlock(&rc->reloc_root_tree.lock);
++               if (!node)
++                       return;
++               BUG_ON((struct btrfs_root *)node->data != root);
+        }
+-       spin_unlock(&rc->reloc_root_tree.lock);
+-
+-       if (!node)
+-               return;
+-       BUG_ON((struct btrfs_root *)node->data != root);
+ 
+        spin_lock(&fs_info->trans_lock);
+        list_del_init(&root->root_list);
+-- 
+
+