Return-path: Received: from mail-pg0-f43.google.com ([74.125.83.43]:33744 "EHLO mail-pg0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933182AbdELQm1 (ORCPT ); Fri, 12 May 2017 12:42:27 -0400 Received: by mail-pg0-f43.google.com with SMTP id u187so32675385pgb.0 for ; Fri, 12 May 2017 09:42:27 -0700 (PDT) From: Brian Norris To: Ganapathi Bhat , Nishant Sarmukadam Cc: , Dmitry Torokhov , Amitkumar Karwar , Kalle Valo , linux-wireless@vger.kernel.org, Doug Anderson , Brian Norris Subject: [PATCH 02/11] mwifiex: Don't release tx_ba_stream_tbl_lock while iterating Date: Fri, 12 May 2017 09:41:59 -0700 Message-Id: <20170512164208.38725-2-briannorris@chromium.org> (sfid-20170512_184515_840364_687B7098) In-Reply-To: <20170512164208.38725-1-briannorris@chromium.org> References: <20170512164208.38725-1-briannorris@chromium.org> Sender: linux-wireless-owner@vger.kernel.org List-ID: From: Douglas Anderson Despite the macro list_for_each_entry_safe() having the word "safe" in the name, it's still not actually safe to release the list spinlock while iterating over the list. The "safe" in the macro name actually only means that it's safe to delete the current entry while iterating over the list. Releasing the spinlock while iterating over the list means that someone else could come in and adjust the list while we don't have the spinlock. If they do that it can totally mix up our iteration and fully corrupt the list. Later iterating over a corrupted list while holding a spinlock and having IRQs off can cause all sorts of hard to debug problems. As evidenced by the other call to mwifiex_11n_delete_tx_ba_stream_tbl_entry() in mwifiex_11n_delete_all_tx_ba_stream_tbl(), it's actually safe to skip the spinlock release. Let's do that. No known problems are fixed by this patch, but it could fix all sorts of weird problems and it should be very safe. Signed-off-by: Douglas Anderson Signed-off-by: Brian Norris --- drivers/net/wireless/marvell/mwifiex/11n.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/drivers/net/wireless/marvell/mwifiex/11n.c b/drivers/net/wireless/marvell/mwifiex/11n.c index c174e79e6df2..c75b6abf16a0 100644 --- a/drivers/net/wireless/marvell/mwifiex/11n.c +++ b/drivers/net/wireless/marvell/mwifiex/11n.c @@ -764,14 +764,9 @@ void mwifiex_del_tx_ba_stream_tbl_by_ra(struct mwifiex_private *priv, u8 *ra) return; spin_lock_irqsave(&priv->tx_ba_stream_tbl_lock, flags); - list_for_each_entry_safe(tbl, tmp, &priv->tx_ba_stream_tbl_ptr, list) { - if (!memcmp(tbl->ra, ra, ETH_ALEN)) { - spin_unlock_irqrestore(&priv->tx_ba_stream_tbl_lock, - flags); + list_for_each_entry_safe(tbl, tmp, &priv->tx_ba_stream_tbl_ptr, list) + if (!memcmp(tbl->ra, ra, ETH_ALEN)) mwifiex_11n_delete_tx_ba_stream_tbl_entry(priv, tbl); - spin_lock_irqsave(&priv->tx_ba_stream_tbl_lock, flags); - } - } spin_unlock_irqrestore(&priv->tx_ba_stream_tbl_lock, flags); return; -- 2.13.0.rc2.291.g57267f2277-goog