From bdb0c28072cc57c6afb0db5fa07c2af3ba5316fa Mon Sep 17 00:00:00 2001
From: Cy Schubert <cy@FreeBSD.org>
Date: Tue, 9 Jan 2018 06:43:58 +0000
Subject: [PATCH] When growing the state, also grow the seed array. Otherwise
 memory that was not allocated will be accessed.

This necessitated refactoring state seed allocation from
ipf_state_soft_init() into a new common ipf_state_seed_alloc() function
as it is now also used by ipf_state_rehash() when changing the size of
the state hash table in addition to by ipf_state_soft_init() during
initialization.

According to Christos Zoulas <christos@NetBSD.org>:

The bug was encountered by a NetBSD vendor who's customer machines had
large ipfilter states. The bug was reliably triggered by resizing the
state variables using "ipf -T".

Submitted by:	Christos Zoulas <christos@NetBSD.org>
Reviewed by:	delphij, rgrimes
Obtained from:	NetBSD ip_state.c CVS revs r1.9 and r1.10
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D13755
---
 sys/contrib/ipfilter/netinet/ip_state.c | 61 +++++++++++++++++--------
 1 file changed, 43 insertions(+), 18 deletions(-)

diff --git a/sys/contrib/ipfilter/netinet/ip_state.c b/sys/contrib/ipfilter/netinet/ip_state.c
index 17eab6619155..1bf190715340 100644
--- a/sys/contrib/ipfilter/netinet/ip_state.c
+++ b/sys/contrib/ipfilter/netinet/ip_state.c
@@ -301,6 +301,32 @@ ipf_state_soft_destroy(softc, arg)
 	KFREE(softs);
 }
 
+static void *
+ipf_state_seed_alloc(u_int state_size, u_int state_max)
+{
+	u_int i;
+	u_long *state_seed;
+	KMALLOCS(state_seed, u_long *, state_size * sizeof(*state_seed));
+	if (state_seed == NULL)
+		return NULL;
+
+	for (i = 0; i < state_size; i++) {
+		/*
+		 * XXX - ipf_state_seed[X] should be a random number of sorts.
+		 */
+#if  FREEBSD_GE_REV(400000)
+		state_seed[i] = arc4random();
+#else
+		state_seed[i] = ((u_long)state_seed + i) * state_size;
+		state_seed[i] ^= 0xa5a55a5a;
+		state_seed[i] *= (u_long)state_seed;
+		state_seed[i] ^= 0x5a5aa5a5;
+		state_seed[i] *= state_max;
+#endif
+	}
+	return state_seed;
+}
+
 
 /* ------------------------------------------------------------------------ */
 /* Function:    ipf_state_soft_init                                         */
@@ -333,27 +359,11 @@ ipf_state_soft_init(softc, arg)
 	bzero((char *)softs->ipf_state_table,
 	      softs->ipf_state_size * sizeof(ipstate_t *));
 
-	KMALLOCS(softs->ipf_state_seed, u_long *,
-		 softs->ipf_state_size * sizeof(*softs->ipf_state_seed));
+	softs->ipf_state_seed = ipf_state_seed_alloc(softs->ipf_state_size,
+	    softs->ipf_state_max);
 	if (softs->ipf_state_seed == NULL)
 		return -2;
 
-	for (i = 0; i < softs->ipf_state_size; i++) {
-		/*
-		 * XXX - ipf_state_seed[X] should be a random number of sorts.
-		 */
-#if  FREEBSD_GE_REV(400000)
-		softs->ipf_state_seed[i] = arc4random();
-#else
-		softs->ipf_state_seed[i] = ((u_long)softs->ipf_state_seed + i) *
-				    softs->ipf_state_size;
-		softs->ipf_state_seed[i] ^= 0xa5a55a5a;
-		softs->ipf_state_seed[i] *= (u_long)softs->ipf_state_seed;
-		softs->ipf_state_seed[i] ^= 0x5a5aa5a5;
-		softs->ipf_state_seed[i] *= softs->ipf_state_max;
-#endif
-	}
-
 	KMALLOCS(softs->ipf_state_stats.iss_bucketlen, u_int *,
 		 softs->ipf_state_size * sizeof(u_int));
 	if (softs->ipf_state_stats.iss_bucketlen == NULL)
@@ -5259,6 +5269,7 @@ ipf_state_rehash(softc, t, p)
 {
 	ipf_state_softc_t *softs = softc->ipf_state_soft;
 	ipstate_t **newtab, *is;
+	u_long *newseed;
 	u_int *bucketlens;
 	u_int maxbucket;
 	u_int newsize;
@@ -5285,6 +5296,14 @@ ipf_state_rehash(softc, t, p)
 		return ENOMEM;
 	}
 
+	newseed = ipf_state_seed_alloc(newsize, softs->ipf_state_max);
+	if (newseed == NULL) {
+		KFREES(bucketlens, newsize * sizeof(*bucketlens));
+		KFREES(newtab, newsize * sizeof(*newtab));
+		IPFERROR(100037);
+		return ENOMEM;
+	}
+
 	for (maxbucket = 0, i = newsize; i > 0; i >>= 1)
 		maxbucket++;
 	maxbucket *= 2;
@@ -5300,6 +5319,12 @@ ipf_state_rehash(softc, t, p)
 	}
 	softs->ipf_state_table = newtab;
 
+	if (softs->ipf_state_seed != NULL) {
+		KFREES(softs->ipf_state_seed,
+		       softs->ipf_state_size * sizeof(*softs->ipf_state_seed));
+	}
+	softs->ipf_state_seed = newseed;
+
 	if (softs->ipf_state_stats.iss_bucketlen != NULL) {
 		KFREES(softs->ipf_state_stats.iss_bucketlen,
 		       softs->ipf_state_size * sizeof(u_int));