commit 03844d8cdb43c351d2c94eb67242966019f7600d
author Pierre Imai <imaipi@google.com> Tue Apr 05 15:49:08 2016 +0900
committer Pierre Imai <imaipi@google.com> Tue Apr 05 16:19:57 2016 +0900
tree 3b14cfa5c9ec93fb225cd3c84a2f4d0e3a1b5ec2
parent 6b3f0d65f2c706625e5efb495df0f2c6178b965a

Fix off-by-one error in res_cache.c

Change-Id: I58264902c123b3bc0d392d17837aa537ca0a3ca2

libc/dns/include/resolv_stats.h

diff --git a/libc/dns/include/resolv_stats.h b/libc/dns/include/resolv_stats.h
index 2aab958..aaf6bd8 100644
--- a/libc/dns/include/resolv_stats.h
+++ b/libc/dns/include/resolv_stats.h
@@ -67,7 +67,7 @@
 
 /* Returns an array of bools indicating which servers are considered good */
 extern void
-_res_stats_get_usable_servers(const struct __res_params* params, struct __res_stats stats[MAXNS],
-        int nscount, bool valid_servers[MAXNS]);
+_res_stats_get_usable_servers(const struct __res_params* params, struct __res_stats stats[],
+        int nscount, bool valid_servers[]);
 
 #endif  // _RES_STATS_H

libc/dns/resolv/res_cache.c

diff --git a/libc/dns/resolv/res_cache.c b/libc/dns/resolv/res_cache.c
index 526c91b..15f9aa4 100644
--- a/libc/dns/resolv/res_cache.c
+++ b/libc/dns/resolv/res_cache.c
@@ -1228,15 +1228,18 @@
     PendingReqInfo   pending_requests;
 } Cache;
 
+// The nameservers[], nsaddrinfo[] and nsstats[] are containing MAXNS + 1 elements, because the
+// number of nameservers is not known and the code relies on the n+1-st entry to be null to
+// recognize the end.
 struct resolv_cache_info {
     unsigned                    netid;
     Cache*                      cache;
     struct resolv_cache_info*   next;
-    char*                       nameservers[MAXNS +1];
+    char*                       nameservers[MAXNS + 1];
     struct addrinfo*            nsaddrinfo[MAXNS + 1];
     int                         revision_id; // # times the nameservers have been replaced
     struct __res_params         params;
-    struct __res_stats          nsstats[MAXNS];
+    struct __res_stats          nsstats[MAXNS + 1];
     char                        defdname[256];
     int                         dnsrch_offset[MAXDNSRCH+1];  // offsets into defdname
 };

libc/dns/resolv/res_send.c

diff --git a/libc/dns/resolv/res_send.c b/libc/dns/resolv/res_send.c
index bfc6e1a..9ceeeb7 100644
--- a/libc/dns/resolv/res_send.c
+++ b/libc/dns/resolv/res_send.c
@@ -488,10 +488,10 @@
 	 * Send request, RETRY times, or until successful.
 	 */
 	for (try = 0; try < statp->retry; try++) {
-	    struct __res_stats stats[MAXNS];
+	    struct __res_stats stats[MAXNS + 1];
 	    struct __res_params params;
 	    int revision_id = _resolv_cache_get_resolver_stats(statp->netid, &params, stats);
-	    bool usable_servers[MAXNS];
+	    bool usable_servers[MAXNS + 1];
 	    _res_stats_get_usable_servers(&params, stats, statp->nscount, usable_servers);
 
 	    for (ns = 0; ns < statp->nscount; ns++) {

libc/dns/resolv/res_stats.c

diff --git a/libc/dns/resolv/res_stats.c b/libc/dns/resolv/res_stats.c
index a3d6f36..b6f5ecb 100644
--- a/libc/dns/resolv/res_stats.c
+++ b/libc/dns/resolv/res_stats.c
@@ -164,8 +164,8 @@
 }
 
 void
-_res_stats_get_usable_servers(const struct __res_params* params, struct __res_stats stats[MAXNS],
-        int nscount, bool usable_servers[MAXNS]) {
+_res_stats_get_usable_servers(const struct __res_params* params, struct __res_stats stats[],
+        int nscount, bool usable_servers[]) {
     unsigned usable_servers_found = 0;
     for (int ns = 0; ns < nscount; ns++) {
         bool usable = _res_stats_usable_server(params, &stats[ns]);