From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Woodhouse Subject: [PATCH 03/17] pppoatm: fix module_put() race Date: Fri, 30 Nov 2012 00:35:22 +0000 Message-ID: <1354235736-26833-4-git-send-email-dwmw2@infradead.org> References: <1354235736-26833-1-git-send-email-dwmw2@infradead.org> Cc: chas@cmf.nrl.navy.mil, krzysiek@podlesie.net, David Woodhouse To: netdev@vger.kernel.org Return-path: Received: from merlin.infradead.org ([205.233.59.134]:37537 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755291Ab2K3Agn (ORCPT ); Thu, 29 Nov 2012 19:36:43 -0500 In-Reply-To: <1354235736-26833-1-git-send-email-dwmw2@infradead.org> Sender: netdev-owner@vger.kernel.org List-ID: From: Krzysztof Mazur The pppoatm used module_put() during unassignment from vcc with hope that we have BKL. This assumption is no longer true. Now owner field in atmvcc is used to move this module_put() to vcc_destroy_socket(). Signed-off-by: Krzysztof Mazur Signed-off-by: David Woodhouse --- net/atm/pppoatm.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/net/atm/pppoatm.c b/net/atm/pppoatm.c index f27a07a..b23c672 100644 --- a/net/atm/pppoatm.c +++ b/net/atm/pppoatm.c @@ -60,6 +60,7 @@ struct pppoatm_vcc { struct atm_vcc *atmvcc; /* VCC descriptor */ void (*old_push)(struct atm_vcc *, struct sk_buff *); void (*old_pop)(struct atm_vcc *, struct sk_buff *); + struct module *old_owner; /* keep old push/pop for detaching */ enum pppoatm_encaps encaps; atomic_t inflight; @@ -155,8 +156,6 @@ static void pppoatm_unassign_vcc(struct atm_vcc *atmvcc) ppp_unregister_channel(&pvcc->chan); atmvcc->user_back = NULL; kfree(pvcc); - /* Gee, I hope we have the big kernel lock here... */ - module_put(THIS_MODULE); } /* Called when an AAL5 PDU comes in */ @@ -165,9 +164,13 @@ static void pppoatm_push(struct atm_vcc *atmvcc, struct sk_buff *skb) struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc); pr_debug("\n"); if (skb == NULL) { /* VCC was closed */ + struct module *module; + pr_debug("removing ATMPPP VCC %p\n", pvcc); + module = pvcc->old_owner; pppoatm_unassign_vcc(atmvcc); atmvcc->push(atmvcc, NULL); /* Pass along bad news */ + module_put(module); return; } atm_return(atmvcc, skb->truesize); @@ -362,6 +365,7 @@ static int pppoatm_assign_vcc(struct atm_vcc *atmvcc, void __user *arg) atomic_set(&pvcc->inflight, NONE_INFLIGHT); pvcc->old_push = atmvcc->push; pvcc->old_pop = atmvcc->pop; + pvcc->old_owner = atmvcc->owner; pvcc->encaps = (enum pppoatm_encaps) be.encaps; pvcc->chan.private = pvcc; pvcc->chan.ops = &pppoatm_ops; @@ -378,6 +382,7 @@ static int pppoatm_assign_vcc(struct atm_vcc *atmvcc, void __user *arg) atmvcc->push = pppoatm_push; atmvcc->pop = pppoatm_pop; __module_get(THIS_MODULE); + atmvcc->owner = THIS_MODULE; /* re-process everything received between connection setup and backend setup */ -- 1.8.0