From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: [PATCH net-next] net: remove unsafe skb_insert() Date: Sun, 25 Nov 2018 08:26:23 -0800 Message-ID: <20181125162623.127762-1-edumazet@google.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Cc: netdev , Eric Dumazet , Eric Dumazet , Faisal Latif , Doug Ledford , Jason Gunthorpe , linux-rdma To: "David S . Miller" Return-path: Received: from mail-pl1-f194.google.com ([209.85.214.194]:38668 "EHLO mail-pl1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726232AbeKZDRz (ORCPT ); Sun, 25 Nov 2018 22:17:55 -0500 Received: by mail-pl1-f194.google.com with SMTP id e5so12677618plb.5 for ; Sun, 25 Nov 2018 08:26:30 -0800 (PST) Sender: netdev-owner@vger.kernel.org List-ID: I do not see how one can effectively use skb_insert() without holding some kind of lock. Otherwise other cpus could have changed the list right before we have a chance of acquiring list->lock. Only existing user is in drivers/infiniband/hw/nes/nes_mgt.c and this one probably meant to use __skb_insert() since it appears nesqp->pau_list is protected by nesqp->pau_lock. This looks like nesqp->pau_lock could be removed, since nesqp->pau_list.lock could be used instead. Signed-off-by: Eric Dumazet Cc: Faisal Latif Cc: Doug Ledford Cc: Jason Gunthorpe Cc: linux-rdma --- drivers/infiniband/hw/nes/nes_mgt.c | 4 ++-- include/linux/skbuff.h | 2 -- net/core/skbuff.c | 22 ---------------------- 3 files changed, 2 insertions(+), 26 deletions(-) diff --git a/drivers/infiniband/hw/nes/nes_mgt.c b/drivers/infiniband/hw/nes/nes_mgt.c index fc0c191014e908eea32d752f3499295ef143aa0a..abb54d30d35dd53fa983ee437506933eeba72746 100644 --- a/drivers/infiniband/hw/nes/nes_mgt.c +++ b/drivers/infiniband/hw/nes/nes_mgt.c @@ -551,14 +551,14 @@ static void queue_fpdus(struct sk_buff *skb, struct nes_vnic *nesvnic, struct ne /* Queue skb by sequence number */ if (skb_queue_len(&nesqp->pau_list) == 0) { - skb_queue_head(&nesqp->pau_list, skb); + __skb_queue_head(&nesqp->pau_list, skb); } else { skb_queue_walk(&nesqp->pau_list, tmpskb) { cb = (struct nes_rskb_cb *)&tmpskb->cb[0]; if (before(seqnum, cb->seqnum)) break; } - skb_insert(tmpskb, skb, &nesqp->pau_list); + __skb_insert(tmpskb, skb, &nesqp->pau_list); } if (nesqp->pau_state == PAU_READY) process_it = true; diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index f17a7452ac7bf47ef4bcf89840bba165cee6f50a..73902acf2b71c8800d81b744a936a7420f33b459 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -1749,8 +1749,6 @@ static inline void skb_queue_head_init_class(struct sk_buff_head *list, * The "__skb_xxxx()" functions are the non-atomic ones that * can only be called with interrupts disabled. */ -void skb_insert(struct sk_buff *old, struct sk_buff *newsk, - struct sk_buff_head *list); static inline void __skb_insert(struct sk_buff *newsk, struct sk_buff *prev, struct sk_buff *next, struct sk_buff_head *list) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 9a8a72cefe9b94d3821b9cc5ba5bba647ae51267..02cd7ae3d0fb26ef0a8b006390154fdefd0d292f 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -2990,28 +2990,6 @@ void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head } EXPORT_SYMBOL(skb_append); -/** - * skb_insert - insert a buffer - * @old: buffer to insert before - * @newsk: buffer to insert - * @list: list to use - * - * Place a packet before a given packet in a list. The list locks are - * taken and this function is atomic with respect to other list locked - * calls. - * - * A buffer cannot be placed on two lists at the same time. - */ -void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list) -{ - unsigned long flags; - - spin_lock_irqsave(&list->lock, flags); - __skb_insert(newsk, old->prev, old, list); - spin_unlock_irqrestore(&list->lock, flags); -} -EXPORT_SYMBOL(skb_insert); - static inline void skb_split_inside_header(struct sk_buff *skb, struct sk_buff* skb1, const u32 len, const int pos) -- 2.20.0.rc0.387.gc7a69e6b6c-goog