[rpcbind PATCH 2/6] rpcbind: bound stats lists in rpcbs_getaddr() and rpcbs_rmtcall()

[Scott Mayhew <smayhew@redhat.com>]

Limit addrinfo and rmtinfo linked lists to 4096 entries by trimming
the oldest entries from the tail after prepending a new one. This
prevents unbounded memory growth from a large number of unique
program/version/netid combinations.

Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
---
 src/rpcb_stat.c | 35 ++++++++++++++++++++++++++++++++---
 1 file changed, 32 insertions(+), 3 deletions(-)

diff --git a/src/rpcb_stat.c b/src/rpcb_stat.c
index 2e5226c..0799a47 100644
--- a/src/rpcb_stat.c
+++ b/src/rpcb_stat.c
@@ -50,6 +50,8 @@
 #include <string.h>
 #include "rpcbind.h"
 
+#define MAX_STAT_BUCKETS 4096
+
 static rpcb_stat_byvers inf;
 
 void
@@ -104,8 +106,9 @@ void
 rpcbs_getaddr(rpcvers_t rtype, rpcprog_t prog, rpcvers_t vers, char *netid,
 	      char *uaddr)
 {
-	rpcbs_addrlist *al;
+	rpcbs_addrlist *al, *cut = NULL, *tmp;
 	struct netconfig *nconf;
+	int listlen = 0;
 
 	if (rtype >= RPCBVERS_STAT)
 		return;
@@ -121,6 +124,9 @@ rpcbs_getaddr(rpcvers_t rtype, rpcprog_t prog, rpcvers_t vers, char *netid,
 				al->success++;
 			return;
 		}
+		listlen++;
+		if (listlen == MAX_STAT_BUCKETS - 1)
+			cut = al;
 	}
 	nconf = rpcbind_get_conf(netid);
 	if (nconf == NULL) {
@@ -142,14 +148,25 @@ rpcbs_getaddr(rpcvers_t rtype, rpcprog_t prog, rpcvers_t vers, char *netid,
 	}
 	al->next = inf[rtype].addrinfo;
 	inf[rtype].addrinfo = al;
+
+	if (cut) {
+		al = cut->next;
+		cut->next = NULL;
+		while (al) {
+			tmp = al;
+			al = al->next;
+			free(tmp);
+		}
+	}
 }
 
 void
 rpcbs_rmtcall(rpcvers_t rtype, rpcproc_t rpcbproc, rpcprog_t prog,
 	      rpcvers_t vers, rpcproc_t proc, char *netid, rpcblist_ptr rbl)
 {
-	rpcbs_rmtcalllist *rl;
+	rpcbs_rmtcalllist *rl, *cut = NULL, *tmp;
 	struct netconfig *nconf;
+	int listlen = 0;
 
 	if (rtype >= RPCBVERS_STAT)
 		return;
@@ -170,6 +187,9 @@ rpcbs_rmtcall(rpcvers_t rtype, rpcproc_t rpcbproc, rpcprog_t prog,
 				rl->indirect++;
 			return;
 		}
+		listlen++;
+		if (listlen == MAX_STAT_BUCKETS - 1)
+			cut = rl;
 	}
 	nconf = rpcbind_get_conf(netid);
 	if (nconf == NULL) {
@@ -194,7 +214,16 @@ rpcbs_rmtcall(rpcvers_t rtype, rpcproc_t rpcbproc, rpcprog_t prog,
 	rl->indirect = 1;
 	rl->next = inf[rtype].rmtinfo;
 	inf[rtype].rmtinfo = rl;
-	return;
+
+	if (cut) {
+		rl = cut->next;
+		cut->next = NULL;
+		while (rl) {
+			tmp = rl;
+			rl = rl->next;
+			free(tmp);
+		}
+	}
 }
 
 void *
-- 
2.55.0