From b01377a4200d0dfc7b04a8daabb4739727353703 Mon Sep 17 00:00:00 2001 From: "sjur.brandeland@stericsson.com" Date: Thu, 2 Feb 2012 01:21:02 +0000 Subject: [PATCH] caif: Bugfix list_del_rcu race in cfmuxl_ctrlcmd. MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Sjur Brændeland Signed-off-by: David S. Miller --- net/caif/cfmuxl.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-) diff --git a/net/caif/cfmuxl.c b/net/caif/cfmuxl.c index b36f24a4c8e7..94b08612a4d8 100644 --- a/net/caif/cfmuxl.c +++ b/net/caif/cfmuxl.c @@ -248,7 +248,6 @@ static void cfmuxl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl, { 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 @@ static void cfmuxl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl, if ((ctrl == _CAIF_CTRLCMD_PHYIF_DOWN_IND || ctrl == CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND) && - layer->id != 0) { - - 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); - } + layer->id != 0) + cfmuxl_remove_uplayer(layr, layer->id); + /* NOTE: ctrlcmd is not allowed to block */ layer->ctrlcmd(layer, ctrl, phyid); } -- 2.20.1