dlm: dlm_process_incoming_buffer() fixes

* check that length is large enough to cover the non-variable part of message or
  rcom resp. (after checking that it's large enough to cover the header, of
  course).

* kill more pointless casts

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

4 files changed, 36 insertions, 24 deletions

diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
index ec61bbaf25d..65499ceaa51 100644
--- a/fs/dlm/dlm_internal.h
+++ b/fs/dlm/dlm_internal.h
@@ -403,6 +403,12 @@ struct dlm_rcom {
         char                    rc_buf[0];
 };
 
+union dlm_packet {
+        struct dlm_header       header;         /* common to other two */
+        struct dlm_message      message;
+        struct dlm_rcom         rcom;
+};
+
 struct rcom_config {
         uint32_t                rf_lvblen;
         uint32_t                rf_lsflags;
diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index d9f07a42e3c..2a28048252e 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -3822,21 +3822,20 @@ void dlm_receive_message_saved(struct dlm_ls *ls, struct dlm_message *ms)
    standard locking activity) or an RCOM (recovery message sent as part of
    lockspace recovery). */
 
-void dlm_receive_buffer(struct dlm_header *hd, int nodeid)
+void dlm_receive_buffer(union dlm_packet *p, int nodeid)
 {
-        struct dlm_message *ms = (struct dlm_message *) hd;
-        struct dlm_rcom *rc = (struct dlm_rcom *) hd;
+        struct dlm_header *hd = &p->header;
         struct dlm_ls *ls;
         int type = 0;
 
         switch (hd->h_cmd) {
         case DLM_MSG:
-                dlm_message_in(ms);
-                type = ms->m_type;
+                dlm_message_in(&p->message);
+                type = p->message.m_type;
                 break;
         case DLM_RCOM:
-                dlm_rcom_in(rc);
-                type = rc->rc_type;
+                dlm_rcom_in(&p->rcom);
+                type = p->rcom.rc_type;
                 break;
         default:
                 log_print("invalid h_cmd %d from %u", hd->h_cmd, nodeid);
@@ -3856,7 +3855,7 @@ void dlm_receive_buffer(struct dlm_header *hd, int nodeid)
                                   hd->h_lockspace, nodeid, hd->h_cmd, type);
 
                 if (hd->h_cmd == DLM_RCOM && type == DLM_RCOM_STATUS)
-                        dlm_send_ls_not_ready(nodeid, rc);
+                        dlm_send_ls_not_ready(nodeid, &p->rcom);
                 return;
         }
 
@@ -3865,9 +3864,9 @@ void dlm_receive_buffer(struct dlm_header *hd, int nodeid)
 
         down_read(&ls->ls_recv_active);
         if (hd->h_cmd == DLM_MSG)
-                dlm_receive_message(ls, ms, nodeid);
+                dlm_receive_message(ls, &p->message, nodeid);
         else
-                dlm_receive_rcom(ls, rc, nodeid);
+                dlm_receive_rcom(ls, &p->rcom, nodeid);
         up_read(&ls->ls_recv_active);
 
         dlm_put_lockspace(ls);
diff --git a/fs/dlm/lock.h b/fs/dlm/lock.h
index 27b6ed30291..05d9c82e646 100644
--- a/fs/dlm/lock.h
+++ b/fs/dlm/lock.h
@@ -17,7 +17,7 @@ void dlm_print_rsb(struct dlm_rsb *r);
 void dlm_dump_rsb(struct dlm_rsb *r);
 void dlm_print_lkb(struct dlm_lkb *lkb);
 void dlm_receive_message_saved(struct dlm_ls *ls, struct dlm_message *ms);
-void dlm_receive_buffer(struct dlm_header *hd, int nodeid);
+void dlm_receive_buffer(union dlm_packet *p, int nodeid);
 int dlm_modes_compat(int mode1, int mode2);
 void dlm_put_rsb(struct dlm_rsb *r);
 void dlm_hold_rsb(struct dlm_rsb *r);
diff --git a/fs/dlm/midcomms.c b/fs/dlm/midcomms.c
index e69926e984d..07ac709f3ed 100644
--- a/fs/dlm/midcomms.c
+++ b/fs/dlm/midcomms.c
@@ -61,9 +61,9 @@ int dlm_process_incoming_buffer(int nodeid, const void *base,
         union {
                 unsigned char __buf[DLM_INBUF_LEN];
                 /* this is to force proper alignment on some arches */
-                struct dlm_header dlm;
+                union dlm_packet p;
         } __tmp;
-        struct dlm_header *msg = &__tmp.dlm;
+        union dlm_packet *p = &__tmp.p;
         int ret = 0;
         int err = 0;
         uint16_t msglen;
@@ -75,15 +75,22 @@ int dlm_process_incoming_buffer(int nodeid, const void *base,
                    message may wrap around the end of the buffer back to the
                    start, so we need to use a temp buffer and copy_from_cb. */
 
-                copy_from_cb(msg, base, offset, sizeof(struct dlm_header),
+                copy_from_cb(p, base, offset, sizeof(struct dlm_header),
                              limit);
 
-                msglen = le16_to_cpu(msg->h_length);
-                lockspace = msg->h_lockspace;
+                msglen = le16_to_cpu(p->header.h_length);
+                lockspace = p->header.h_lockspace;
 
                 err = -EINVAL;
                 if (msglen < sizeof(struct dlm_header))
                         break;
+                if (p->header.h_cmd == DLM_MSG) {
+                        if (msglen < sizeof(struct dlm_message))
+                                break;
+                } else {
+                        if (msglen < sizeof(struct dlm_rcom))
+                                break;
+                }
                 err = -E2BIG;
                 if (msglen > dlm_config.ci_buffer_size) {
                         log_print("message size %d from %d too big, buf len %d",
@@ -104,26 +111,26 @@ int dlm_process_incoming_buffer(int nodeid, const void *base,
                    in the buffer on the stack (which should work for most
                    ordinary messages). */
 
-                if (msglen > DLM_INBUF_LEN && msg == &__tmp.dlm) {
-                        msg = kmalloc(dlm_config.ci_buffer_size, GFP_KERNEL);
-                        if (msg == NULL)
+                if (msglen > sizeof(__tmp) && p == &__tmp.p) {
+                        p = kmalloc(dlm_config.ci_buffer_size, GFP_KERNEL);
+                        if (p == NULL)
                                 return ret;
                 }
 
-                copy_from_cb(msg, base, offset, msglen, limit);
+                copy_from_cb(p, base, offset, msglen, limit);
 
-                BUG_ON(lockspace != msg->h_lockspace);
+                BUG_ON(lockspace != p->header.h_lockspace);
 
                 ret += msglen;
                 offset += msglen;
                 offset &= (limit - 1);
                 len -= msglen;
 
-                dlm_receive_buffer(msg, nodeid);
+                dlm_receive_buffer(p, nodeid);
         }
 
-        if (msg != &__tmp.dlm)
-                kfree(msg);
+        if (p != &__tmp.p)
+                kfree(p);
 
         return err ? err : ret;
 }