linux-kernel - [PATCH 04/14] mwifiex: pcie: don't allow cmd buffer reuse after reset

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Message-Id: <20170525001119.64791-4-briannorris@chromium.org>
Date:   Wed, 24 May 2017 17:11:09 -0700
From:   Brian Norris <briannorris@...omium.org>
To:     Ganapathi Bhat <gbhat@...vell.com>,
        Nishant Sarmukadam <nishants@...vell.com>
Cc:     <linux-kernel@...r.kernel.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Amitkumar Karwar <amitkarwar@...il.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        linux-wireless@...r.kernel.org,
        Brian Norris <briannorris@...omium.org>
Subject: [PATCH 04/14] mwifiex: pcie: don't allow cmd buffer reuse after reset

In rogue cases (due to other bugs) it's possible we try to process an
old command response *after* resetting the device. This could trigger a
double-free (or the SKB can get reallocated elsewhere...causing other
memory corruptions) in mwifiex_pcie_process_cmd_complete().

For safety (and symmetry) let's always NULL out the command buffer as we
free it up. We're already doing this for the command response buffer.

Signed-off-by: Brian Norris <briannorris@...omium.org>
---
 drivers/net/wireless/marvell/mwifiex/pcie.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/pcie.c b/drivers/net/wireless/marvell/mwifiex/pcie.c
index ea75315bf19d..3d5c29d79609 100644
--- a/drivers/net/wireless/marvell/mwifiex/pcie.c
+++ b/drivers/net/wireless/marvell/mwifiex/pcie.c
@@ -1060,12 +1060,14 @@ static int mwifiex_pcie_delete_cmdrsp_buf(struct mwifiex_adapter *adapter)
 		mwifiex_unmap_pci_memory(adapter, card->cmdrsp_buf,
 					 PCI_DMA_FROMDEVICE);
 		dev_kfree_skb_any(card->cmdrsp_buf);
+		card->cmdrsp_buf = NULL;
 	}
 
 	if (card && card->cmd_buf) {
 		mwifiex_unmap_pci_memory(adapter, card->cmd_buf,
 					 PCI_DMA_TODEVICE);
 		dev_kfree_skb_any(card->cmd_buf);
+		card->cmd_buf = NULL;
 	}
 	return 0;
 }
@@ -2946,7 +2948,6 @@ static void mwifiex_pcie_free_buffers(struct mwifiex_adapter *adapter)
 	mwifiex_pcie_delete_evtbd_ring(adapter);
 	mwifiex_pcie_delete_rxbd_ring(adapter);
 	mwifiex_pcie_delete_txbd_ring(adapter);
-	card->cmdrsp_buf = NULL;
 }
 
 /*
-- 
2.13.0.219.gdb65acc882-goog