| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.14 010/159] xfrm: fix rcu usage in xfrm_get_type_offload | Date | Fri, 23 Feb 2018 19:25:18 +0100 |
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4.14-stable review patch. If anyone has any objections, please let me know.
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From: Sabrina Dubroca <sd@queasysnail.net>
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@syzkaller.appspotmail.com Signed-off-by: Sabrina Dubroca <sd@queasysnail.net> Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- 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; }
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