From 926f38e9744b2ee6d92085c28ebb50744e9e1182 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Thu, 22 Jun 2017 18:57:55 -0700 Subject: [PATCH] tcp: fix out-of-bounds access in ULP sysctl KASAN reports out-of-bound access in proc_dostring() coming from proc_tcp_available_ulp() because in case TCP ULP list is empty the buffer allocated for the response will not have anything printed into it. Set the first byte to zero to avoid strlen() going out-of-bounds. Fixes: 734942cc4ea6 ("tcp: ULP infrastructure") Signed-off-by: Jakub Kicinski Signed-off-by: David S. Miller --- net/ipv4/tcp_ulp.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/ipv4/tcp_ulp.c b/net/ipv4/tcp_ulp.c index e855ea7..2417f55 100644 --- a/net/ipv4/tcp_ulp.c +++ b/net/ipv4/tcp_ulp.c @@ -88,6 +88,7 @@ void tcp_get_available_ulp(char *buf, size_t maxlen) struct tcp_ulp_ops *ulp_ops; size_t offs = 0; + *buf = '\0'; rcu_read_lock(); list_for_each_entry_rcu(ulp_ops, &tcp_ulp_list, list) { offs += snprintf(buf + offs, maxlen - offs, -- 2.7.4