net: sctp: fix array overrun read on sctp_timer_tbl

Table sctp_timer_tbl is missing a TIMEOUT_RECONF string so
add this in. Also compare timeout with the size of the array
sctp_timer_tbl rather than SCTP_EVENT_TIMEOUT_MAX.  Also add
a build time check that SCTP_EVENT_TIMEOUT_MAX is correct
so we don't ever get this kind of mismatch between the table
and SCTP_EVENT_TIMEOUT_MAX in the future.

Kudos to Marcelo Ricardo Leitner for spotting the missing string
and suggesting the build time sanity check.

Fixes CoverityScan CID#1397639 ("Out-of-bounds read")

Fixes: 7b9438de0cd4 ("sctp: add stream reconf timer")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 1 deletions

diff --git a/net/sctp/debug.c b/net/sctp/debug.c
index 95d7b15dad21..2e47eb2f05cb 100644
--- a/net/sctp/debug.c
+++ b/net/sctp/debug.c
@@ -159,6 +159,7 @@ static const char *const sctp_timer_tbl[] = {
         "TIMEOUT_T4_RTO",
         "TIMEOUT_T5_SHUTDOWN_GUARD",
         "TIMEOUT_HEARTBEAT",
+        "TIMEOUT_RECONF",
         "TIMEOUT_SACK",
         "TIMEOUT_AUTOCLOSE",
 };
@@ -166,7 +167,9 @@ static const char *const sctp_timer_tbl[] = {
 /* Lookup timer debug name. */
 const char *sctp_tname(const sctp_subtype_t id)
 {
-        if (id.timeout <= SCTP_EVENT_TIMEOUT_MAX)
+        BUILD_BUG_ON(SCTP_EVENT_TIMEOUT_MAX + 1 != ARRAY_SIZE(sctp_timer_tbl));
+
+        if (id.timeout < ARRAY_SIZE(sctp_timer_tbl))
                 return sctp_timer_tbl[id.timeout];
         return "unknown_timer";
 }