Commit 2f10a61c authored Dec 31, 2017 by Sabrina Dubroca Committed by Steffen Klassert Dec 31, 2017

xfrm: fix rcu usage in xfrm_get_type_offload

request_module can sleep, thus we cannot hold rcu_read_lock() while
calling it. The function also jumps back and takes rcu_read_lock()
again (in xfrm_state_get_afinfo()), resulting in an imbalance.

This codepath is triggered whenever a new offloaded state is created.

Fixes: ffdb5211 ("xfrm: Auto-load xfrm offload modules")
Reported-by: <syzbot+ca425f44816d749e8eb49755567a75ee48cf4a30@syzkaller.appspotmail.com>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

parent 4e765b49

net/xfrm/xfrm_state.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -313,13 +313,14 @@ xfrm_get_type_offload(u8 proto, unsigned short family, bool try_load)
		if ((type && !try_module_get(type->owner)))
		type = NULL;

		rcu_read_unlock();

		if (!type && try_load) {
		request_module("xfrm-offload-%d-%d", family, proto);
		try_load = 0;
		goto retry;
		}

		rcu_read_unlock();
		return type;
		}