4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Sabrina Dubroca <sd@xxxxxxxxxxxxxxx>
commit 2f10a61cee8fdb9f8da90f5db687e1862b22cf06 upstream.
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: ffdb5211da1c ("xfrm: Auto-load xfrm offload modules")
Reported-by: syzbot+ca425f44816d749e8eb49755567a75ee48cf4a30@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Sabrina Dubroca <sd@xxxxxxxxxxxxxxx>
Signed-off-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/xfrm/xfrm_state.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -313,13 +313,14 @@ retry:
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;
}