five small SMB3 fixes, all also for stable - an important fix for an oplock (lease) bug, a handle leak, and 3 bugs spotted by KASAN

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Merge tag '5.1-rc5-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6

Pull smb3 fixes from Steve French:
 "Five small SMB3 fixes, all also for stable - an important fix for an
  oplock (lease) bug, a handle leak, and three bugs spotted by KASAN"

* tag '5.1-rc5-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  CIFS: keep FileInfo handle live during oplock break
  cifs: fix handle leak in smb2_query_symlink()
  cifs: Fix lease buffer length error
  cifs: Fix use-after-free in SMB2_read
  cifs: Fix use-after-free in SMB2_write

fs/cifs/cifsglob.h

@@ -1333,6 +1333,7 @@ cifsFileInfo_get_locked(struct cifsFileInfo *cifs_file)
 }
 
 struct cifsFileInfo *cifsFileInfo_get(struct cifsFileInfo *cifs_file);
+void _cifsFileInfo_put(struct cifsFileInfo *cifs_file, bool wait_oplock_hdlr);
 void cifsFileInfo_put(struct cifsFileInfo *cifs_file);
 
 #define CIFS_CACHE_READ_FLG	1
@@ -1855,6 +1856,7 @@ GLOBAL_EXTERN spinlock_t gidsidlock;
 #endif /* CONFIG_CIFS_ACL */
 
 void cifs_oplock_break(struct work_struct *work);
+void cifs_queue_oplock_break(struct cifsFileInfo *cfile);
 
 extern const struct slow_work_ops cifs_oplock_break_ops;
 extern struct workqueue_struct *cifsiod_wq;

fs/cifs/file.c

@@ -360,12 +360,30 @@ cifsFileInfo_get(struct cifsFileInfo *cifs_file)
 	return cifs_file;
 }
 
-/*
- * Release a reference on the file private data. This may involve closing
- * the filehandle out on the server. Must be called without holding
- * tcon->open_file_lock and cifs_file->file_info_lock.
+/**
+ * cifsFileInfo_put - release a reference of file priv data
+ *
+ * Always potentially wait for oplock handler. See _cifsFileInfo_put().
  */
 void cifsFileInfo_put(struct cifsFileInfo *cifs_file)
+{
+	_cifsFileInfo_put(cifs_file, true);
+}
+
+/**
+ * _cifsFileInfo_put - release a reference of file priv data
+ *
+ * This may involve closing the filehandle @cifs_file out on the
+ * server. Must be called without holding tcon->open_file_lock and
+ * cifs_file->file_info_lock.
+ *
+ * If @wait_for_oplock_handler is true and we are releasing the last
+ * reference, wait for any running oplock break handler of the file
+ * and cancel any pending one. If calling this function from the
+ * oplock break handler, you need to pass false.
+ *
+ */
+void _cifsFileInfo_put(struct cifsFileInfo *cifs_file, bool wait_oplock_handler)
 {
 	struct inode *inode = d_inode(cifs_file->dentry);
 	struct cifs_tcon *tcon = tlink_tcon(cifs_file->tlink);
@@ -414,7 +432,8 @@ void cifsFileInfo_put(struct cifsFileInfo *cifs_file)
 
 	spin_unlock(&tcon->open_file_lock);
 
-	oplock_break_cancelled = cancel_work_sync(&cifs_file->oplock_break);
+	oplock_break_cancelled = wait_oplock_handler ?
+		cancel_work_sync(&cifs_file->oplock_break) : false;
 
 	if (!tcon->need_reconnect && !cifs_file->invalidHandle) {
 		struct TCP_Server_Info *server = tcon->ses->server;
@@ -4603,6 +4622,7 @@ void cifs_oplock_break(struct work_struct *work)
 							     cinode);
 		cifs_dbg(FYI, "Oplock release rc = %d\n", rc);
 	}
+	_cifsFileInfo_put(cfile, false /* do not wait for ourself */);
 	cifs_done_oplock_break(cinode);
 }
 

fs/cifs/misc.c

@@ -501,8 +501,7 @@ is_valid_oplock_break(char *buffer, struct TCP_Server_Info *srv)
 					   CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
 					   &pCifsInode->flags);
 
-				queue_work(cifsoplockd_wq,
-					   &netfile->oplock_break);
+				cifs_queue_oplock_break(netfile);
 				netfile->oplock_break_cancelled = false;
 
 				spin_unlock(&tcon->open_file_lock);
@@ -607,6 +606,28 @@ void cifs_put_writer(struct cifsInodeInfo *cinode)
 	spin_unlock(&cinode->writers_lock);
 }
 
+/**
+ * cifs_queue_oplock_break - queue the oplock break handler for cfile
+ *
+ * This function is called from the demultiplex thread when it
+ * receives an oplock break for @cfile.
+ *
+ * Assumes the tcon->open_file_lock is held.
+ * Assumes cfile->file_info_lock is NOT held.
+ */
+void cifs_queue_oplock_break(struct cifsFileInfo *cfile)
+{
+	/*
+	 * Bump the handle refcount now while we hold the
+	 * open_file_lock to enforce the validity of it for the oplock
+	 * break handler. The matching put is done at the end of the
+	 * handler.
+	 */
+	cifsFileInfo_get(cfile);
+
+	queue_work(cifsoplockd_wq, &cfile->oplock_break);
+}
+
 void cifs_done_oplock_break(struct cifsInodeInfo *cinode)
 {
 	clear_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags);

fs/cifs/smb2misc.c

@@ -555,7 +555,7 @@ smb2_tcon_has_lease(struct cifs_tcon *tcon, struct smb2_lease_break *rsp,
 			clear_bit(CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
 				  &cinode->flags);
 
-		queue_work(cifsoplockd_wq, &cfile->oplock_break);
+		cifs_queue_oplock_break(cfile);
 		kfree(lw);
 		return true;
 	}
@@ -712,8 +712,8 @@ smb2_is_valid_oplock_break(char *buffer, struct TCP_Server_Info *server)
 					   CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
 					   &cinode->flags);
 				spin_unlock(&cfile->file_info_lock);
-				queue_work(cifsoplockd_wq,
-					   &cfile->oplock_break);
+
+				cifs_queue_oplock_break(cfile);
 
 				spin_unlock(&tcon->open_file_lock);
 				spin_unlock(&cifs_tcp_ses_lock);

fs/cifs/smb2ops.c

@@ -2389,6 +2389,8 @@ smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon,
 
 	rc = SMB2_open(xid, &oparms, utf16_path, &oplock, NULL, &err_iov,
 		       &resp_buftype);
+	if (!rc)
+		SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
 	if (!rc || !err_iov.iov_base) {
 		rc = -ENOENT;
 		goto free_path;

fs/cifs/smb2pdu.c

@@ -832,8 +832,11 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
 		} else if (rsp->DialectRevision == cpu_to_le16(SMB21_PROT_ID)) {
 			/* ops set to 3.0 by default for default so update */
 			ses->server->ops = &smb21_operations;
-		} else if (rsp->DialectRevision == cpu_to_le16(SMB311_PROT_ID))
+			ses->server->vals = &smb21_values;
+		} else if (rsp->DialectRevision == cpu_to_le16(SMB311_PROT_ID)) {
 			ses->server->ops = &smb311_operations;
+			ses->server->vals = &smb311_values;
+		}
 	} else if (le16_to_cpu(rsp->DialectRevision) !=
 				ses->server->vals->protocol_id) {
 		/* if requested single dialect ensure returned dialect matched */
@@ -3448,8 +3451,6 @@ SMB2_read(const unsigned int xid, struct cifs_io_parms *io_parms,
 	rqst.rq_nvec = 1;
 
 	rc = cifs_send_recv(xid, ses, &rqst, &resp_buftype, flags, &rsp_iov);
-	cifs_small_buf_release(req);
-
 	rsp = (struct smb2_read_rsp *)rsp_iov.iov_base;
 
 	if (rc) {
@@ -3471,6 +3472,8 @@ SMB2_read(const unsigned int xid, struct cifs_io_parms *io_parms,
 				    io_parms->tcon->tid, ses->Suid,
 				    io_parms->offset, io_parms->length);
 
+	cifs_small_buf_release(req);
+
 	*nbytes = le32_to_cpu(rsp->DataLength);
 	if ((*nbytes > CIFS_MAX_MSGSIZE) ||
 	    (*nbytes > io_parms->length)) {
@@ -3769,7 +3772,6 @@ SMB2_write(const unsigned int xid, struct cifs_io_parms *io_parms,
 
 	rc = cifs_send_recv(xid, io_parms->tcon->ses, &rqst,
 			    &resp_buftype, flags, &rsp_iov);
-	cifs_small_buf_release(req);
 	rsp = (struct smb2_write_rsp *)rsp_iov.iov_base;
 
 	if (rc) {
@@ -3787,6 +3789,7 @@ SMB2_write(const unsigned int xid, struct cifs_io_parms *io_parms,
 				     io_parms->offset, *nbytes);
 	}
 
+	cifs_small_buf_release(req);
 	free_rsp_buf(resp_buftype, rsp);
 	return rc;
 }