From 5967b22698c8aeb51131a62c56a2f7fbf1f8e79e Mon Sep 17 00:00:00 2001
From: Derrick Brashear <shadow@dementia.org>
Date: Wed, 2 Apr 2003 01:22:16 +0000
Subject: [PATCH] h-gethost-r-race-20030401

FIXES 1308

Thanks to Chaskiel Grundman for explaining what was happening:
- the connection is old and pre-existing, but has no host structure.
- 2 calls come in
- the first one enters h_GetHost_r, and h_Lookup_r returns null (but identP is
non-null, since rx keeps it around until it gc's the connection)
  The first thread calls WhoAreYou, which succeeds, it then calls
InitCallBackState3 (after H_UNLOCK) note that the host has been inserted into
the hashtable
- the second thread enters h_GetHost_r, and calls rx_GetSpecific. it then
calls h_Lookup_r. h_Lookup_r will block (new host is locked), but eventually
returns the new host
- InitCallBackState3 returns, and the frees the old identP, replaces it, and
unlocks the host.
- the first thread returns from h_Lookup_r. boom.

the changes:
-call rx_GetSpecific after h_Lookup_r returns (and potentially slept)
-removes an if wrapping which always is true (since !interfValid is always
 true)
-don't realloc identP if it exists
-don't free an old one by calling rx_SetSpecific either
---
 src/viced/host.c | 69 ++++++++++++++++++++++++++++++++------------------------
 1 file changed, 40 insertions(+), 29 deletions(-)

diff --git a/src/viced/host.c b/src/viced/host.c
index 7b2f8de..8904910 100644
--- a/src/viced/host.c
+++ b/src/viced/host.c
@@ -943,8 +943,8 @@ retry:
     caps.Capabilities_len = 0;
 
     code = 0;
-    identP = (struct Identity *)rx_GetSpecific(tcon, rxcon_ident_key);
     host = h_Lookup_r(haddr, hport, &held);
+    identP = (struct Identity *)rx_GetSpecific(tcon, rxcon_ident_key);
     if (host && !identP && !(host->Console&1)) {
 	/* This is a new connection, and we already have a host
 	 * structure for this address. Verify that the identity
@@ -1069,39 +1069,50 @@ retry:
 	host = h_Alloc_r(tcon); /* returned held and locked */
 	h_gethostcps_r(host,FT_ApproxTime());
         if (!(host->Console&1)) {
-	    if (!identP || !interfValid) {
-		H_UNLOCK
-		code = RXAFSCB_TellMeAboutYourself(host->callback_rxcon, 
-						   &interf, &caps);
-		if ( code == RXGEN_OPCODE ) 
-		    code = RXAFSCB_WhoAreYou(host->callback_rxcon, &interf);
-		H_LOCK
-		if ( code == RXGEN_OPCODE ) {
+	    int pident = 0;
+	    H_UNLOCK
+	    code = RXAFSCB_TellMeAboutYourself(host->callback_rxcon, 
+					       &interf, &caps);
+	    if ( code == RXGEN_OPCODE ) 
+		code = RXAFSCB_WhoAreYou(host->callback_rxcon, &interf);
+	    H_LOCK
+	    if ( code == RXGEN_OPCODE ) {
+		if (!identP)
 		    identP = (struct Identity *)malloc(sizeof(struct Identity));
-		    if (!identP) {
-			ViceLog(0, ("Failed malloc in h_GetHost_r\n"));
-			assert(0);
-		    }
-		    identP->valid = 0;
+		else
+		    pident = 1;
+
+		if (!identP) {
+		    ViceLog(0, ("Failed malloc in h_GetHost_r\n"));
+		    assert(0);
+		}
+		identP->valid = 0;
+		if (!pident)
 		    rx_SetSpecific(tcon, rxcon_ident_key, identP);
-		    ViceLog(25,
-			    ("Host %s:%d does not support WhoAreYou.\n",
-			    afs_inet_ntoa_r(host->host, hoststr), ntohs(host->port)));
-		    code = 0;
-		} else if (code == 0) {
-		    interfValid = 1;
+		ViceLog(25,
+			("Host %s:%d does not support WhoAreYou.\n",
+			 afs_inet_ntoa_r(host->host, hoststr), 
+			 ntohs(host->port)));
+		code = 0;
+	    } else if (code == 0) {
+		if (!identP)
 		    identP = (struct Identity *)malloc(sizeof(struct Identity));
-		    if (!identP) {
-			ViceLog(0, ("Failed malloc in h_GetHost_r\n"));
-			assert(0);
-		    }
-		    identP->valid = 1;
-		    identP->uuid = interf.uuid;
-		    rx_SetSpecific(tcon, rxcon_ident_key, identP);
-		    ViceLog(25, ("WhoAreYou success on %s:%d\n",
-				afs_inet_ntoa_r(host->host, hoststr), ntohs(host->port)));
+		else 
+		    pident = 1;
+
+		if (!identP) {
+		    ViceLog(0, ("Failed malloc in h_GetHost_r\n"));
+		    assert(0);
 		}
+		identP->valid = 1;
+		identP->uuid = interf.uuid;
+		if (!pident)
+		    rx_SetSpecific(tcon, rxcon_ident_key, identP);
+		ViceLog(25, ("WhoAreYou success on %s:%d\n",
+			     afs_inet_ntoa_r(host->host, hoststr), 
+			     ntohs(host->port)));
 	    }
+	    interfValid=identP->valid;
 	    if (code == 0 && !identP->valid) {
 	 	H_UNLOCK
 		code = RXAFSCB_InitCallBackState(host->callback_rxcon);
-- 
1.9.4