caif: Bugfix list_del_rcu race in cfmuxl_ctrlcmd.
Always use cfmuxl_remove_uplayer when removing a up-layer.
cfmuxl_ctrlcmd() can be called independently and in parallel with
cfmuxl_remove_uplayer(). The race between them could cause list_del_rcu
to be called on a node which has been already taken out from the list.
That lead to a (rare) crash on accessing poisoned node->prev inside
list_del_rcu.
This fix ensures that deletion are done holding the same lock.
Reported-by: Dmitry Tarnyagin <dmitry.tarnyagin@stericsson.com>
Signed-off-by: Sjur Brændeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/caif/cfmuxl.c b/net/caif/cfmuxl.c
index b36f24a..94b0861 100644
--- a/net/caif/cfmuxl.c
+++ b/net/caif/cfmuxl.c
@@ -248,7 +248,6 @@
{
struct cfmuxl *muxl = container_obj(layr);
struct cflayer *layer;
- int idx;
rcu_read_lock();
list_for_each_entry_rcu(layer, &muxl->srvl_list, node) {
@@ -257,14 +256,9 @@
if ((ctrl == _CAIF_CTRLCMD_PHYIF_DOWN_IND ||
ctrl == CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND) &&
- layer->id != 0) {
+ layer->id != 0)
+ cfmuxl_remove_uplayer(layr, layer->id);
- idx = layer->id % UP_CACHE_SIZE;
- spin_lock_bh(&muxl->receive_lock);
- RCU_INIT_POINTER(muxl->up_cache[idx], NULL);
- list_del_rcu(&layer->node);
- spin_unlock_bh(&muxl->receive_lock);
- }
/* NOTE: ctrlcmd is not allowed to block */
layer->ctrlcmd(layer, ctrl, phyid);
}