This is a note to let you know that I've just added the patch titled
xfrm: fix rcu usage in xfrm_get_type_offload
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
xfrm-fix-rcu-usage-in-xfrm_get_type_offload.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 2f10a61cee8fdb9f8da90f5db687e1862b22cf06 Mon Sep 17 00:00:00 2001
From: Sabrina Dubroca <sd@xxxxxxxxxxxxxxx>
Date: Sun, 31 Dec 2017 16:18:56 +0100
Subject: xfrm: fix rcu usage in xfrm_get_type_offload
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;
}
Patches currently in stable-queue which might be from sd@xxxxxxxxxxxxxxx are
queue-4.14/xfrm-fix-rcu-usage-in-xfrm_get_type_offload.patch