Commit 926f38e9 authored Jun 22, 2017 by Jakub Kicinski Committed by David S. Miller Jun 23, 2017

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: 734942cc ("tcp: ULP infrastructure")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 23994631

net/ipv4/tcp_ulp.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -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,