dlm: validate data in dlm_recover_directory()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Teigland <teigland@redhat.com>

1 files changed, 20 insertions, 3 deletions

diff --git a/fs/dlm/dir.c b/fs/dlm/dir.c
index ce30136671b3..831050e5bfd5 100644
--- a/fs/dlm/dir.c
+++ b/fs/dlm/dir.c
@@ -220,6 +220,7 @@ int dlm_recover_directory(struct dlm_ls *ls)
                 last_len = 0;
 
                 for (;;) {
+                        int left;
                         error = dlm_recovery_stopped(ls);
                         if (error)
                                 goto out_free;
@@ -236,11 +237,20 @@ int dlm_recover_directory(struct dlm_ls *ls)
                          */
 
                         b = ls->ls_recover_buf->rc_buf;
+                        left = ls->ls_recover_buf->rc_header.h_length;
+                        left -= sizeof(struct dlm_rcom);
 
                         for (;;) {
-                                memcpy(&namelen, b, sizeof(uint16_t));
-                                namelen = be16_to_cpu(namelen);
-                                b += sizeof(uint16_t);
+                                __be16 v;
+
+                                error = -EINVAL;
+                                if (left < sizeof(__be16))
+                                        goto out_free;
+
+                                memcpy(&v, b, sizeof(__be16));
+                                namelen = be16_to_cpu(v);
+                                b += sizeof(__be16);
+                                left -= sizeof(__be16);
 
                                 /* namelen of 0xFFFFF marks end of names for
                                    this node; namelen of 0 marks end of the
@@ -251,6 +261,12 @@ int dlm_recover_directory(struct dlm_ls *ls)
                                 if (!namelen)
                                         break;
 
+                                if (namelen > left)
+                                        goto out_free;
+
+                                if (namelen > DLM_RESNAME_MAXLEN)
+                                        goto out_free;
+
                                 error = -ENOMEM;
                                 de = get_free_de(ls, namelen);
                                 if (!de)
@@ -262,6 +278,7 @@ int dlm_recover_directory(struct dlm_ls *ls)
                                 memcpy(de->name, b, namelen);
                                 memcpy(last_name, b, namelen);
                                 b += namelen;
+                                left -= namelen;
 
                                 add_entry_to_hash(ls, de);
                                 count++;