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>

diff --git a/fs/dlm/dir.c b/fs/dlm/dir.c
index ce30136671b3f755e27233f9566edce1414b9f54..831050e5bfd59529359904b64cbcb81b215508a0 100644 (file)
--- 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++;