From d701cb4100474ed1b2fd3eeed6193bff4407ed5c 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: 591678870c9f ("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 e855ea70819b6..2417f55374c59 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, -- 2.39.5