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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: ffdb5211da ("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>
This commit is contained in:
Sabrina Dubroca 2017-12-31 16:18:56 +01:00 committed by Steffen Klassert
parent 4e765b4972
commit 2f10a61cee
1 changed files with 2 additions and 1 deletions
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3
net/xfrm/xfrm_state.c
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@ -313,13 +313,14 @@ retry:
if ((type && !try_module_get(type->owner))) if ((type && !try_module_get(type->owner)))
type = NULL; type = NULL;
rcu_read_unlock();
if (!type && try_load) { if (!type && try_load) {
request_module("xfrm-offload-%d-%d", family, proto); request_module("xfrm-offload-%d-%d", family, proto);
try_load = 0; try_load = 0;
goto retry; goto retry;
} }
rcu_read_unlock();
return type; return type;
} }