[PATCH for v4.9 LTS 35/86] net: sctp: fix array overrun read on sctp_timer_tbl

[Levin, Alexander (Sasha Levin)]

From: Colin Ian King <colin.king@xxxxxxxxxxxxx>

[ Upstream commit 0e73fc9a56f22f2eec4d2b2910c649f7af67b74d ]

The comparison on the timeout can lead to an array overrun
read on sctp_timer_tbl because of an off-by-one error. Fix
this by using < instead of <= and also compare to the array
size rather than SCTP_EVENT_TIMEOUT_MAX.

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

Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
---
 net/sctp/debug.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sctp/debug.c b/net/sctp/debug.c
index 95d7b15dad21..e371a0d90068 100644
--- a/net/sctp/debug.c
+++ b/net/sctp/debug.c
@@ -166,7 +166,7 @@ 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)
+	if (id.timeout < ARRAY_SIZE(sctp_timer_tbl))
 		return sctp_timer_tbl[id.timeout];
 	return "unknown_timer";
 }
-- 
2.11.0