s3: smbd: Fix SMB1 use-after-free crash bug. CVE-2017-14746

When setting up the chain, always use 'next->' variables not the 'req->' one. Bug discovered by 连一汉 <lianyihan@360.cn> BUG: https://bugzilla.samba.org/show_bug.cgi?id=13041 Signed-off-by: Jeremy Allison <jra@samba.org>
samba-team · Nov 21, 2017 · deda043 · deda043
1 parent 8212c34
commit deda043
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Showing 2 changed files with 9 additions and 3 deletions.
diff --git a/source3/smbd/process.c b/source3/smbd/process.c
@@ -1855,12 +1855,13 @@ void smb_request_done(struct smb_request *req)
 
 		next->vuid = SVAL(req->outbuf, smb_uid);
 		next->tid  = SVAL(req->outbuf, smb_tid);
-		status = smb1srv_tcon_lookup(req->xconn, req->tid,
+		status = smb1srv_tcon_lookup(req->xconn, next->tid,
 					     now, &tcon);
+
 		if (NT_STATUS_IS_OK(status)) {
-			req->conn = tcon->compat;
+			next->conn = tcon->compat;
 		} else {
-			req->conn = NULL;
+			next->conn = NULL;
 		}
 		next->chain_fsp = req->chain_fsp;
 		next->inbuf = req->inbuf;

diff --git a/source3/smbd/reply.c b/source3/smbd/reply.c
@@ -923,6 +923,11 @@ void reply_tcon_and_X(struct smb_request *req)
 		}
 
 		TALLOC_FREE(tcon);
+		/*
+		 * This tree id is gone. Make sure we can't re-use it
+		 * by accident.
+		 */
+		req->tid = 0;
 	}
 
 	if ((passlen > MAX_PASS_LEN) || (passlen >= req->buflen)) {