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Subject[PATCH 3.19 080/101] rtlwifi: Fix IOMMU mapping leak in AP mode
3.19-stable review patch.  If anyone has any objections, please let me know.


From: Larry Finger <>

commit be0b5e635883678bfbc695889772fed545f3427d upstream.

Transmission of an AP beacon does not call the TX interrupt service routine,
which usually does the cleanup. Instead, cleanup is handled in a tasklet
completion routine. Unfortunately, this routine has a serious bug in that it does
not release the DMA mapping before it frees the skb, thus one IOMMU mapping is
leaked for each beacon. The test system failed with no free IOMMU mapping slots
approximately one hour after hostapd was used to start an AP.

This issue was reported and tested at

Reported-and-tested-by: Kevin Mullican <>
Cc: Kevin Mullican <>
Signed-off-by: Shao Fu <>
Signed-off-by: Larry Finger <>
Signed-off-by: Kalle Valo <>
Signed-off-by: Greg Kroah-Hartman <>

drivers/net/wireless/rtlwifi/pci.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

--- a/drivers/net/wireless/rtlwifi/pci.c
+++ b/drivers/net/wireless/rtlwifi/pci.c
@@ -1118,12 +1118,22 @@ static void _rtl_pci_prepare_bcn_tasklet
/*This is for new trx flow*/
struct rtl_tx_buffer_desc *pbuffer_desc = NULL;
u8 temp_one = 1;
+ u8 *entry;

memset(&tcb_desc, 0, sizeof(struct rtl_tcb_desc));
ring = &rtlpci->tx_ring[BEACON_QUEUE];
pskb = __skb_dequeue(&ring->queue);
- if (pskb)
+ if (rtlpriv->use_new_trx_flow)
+ entry = (u8 *)(&ring->buffer_desc[ring->idx]);
+ else
+ entry = (u8 *)(&ring->desc[ring->idx]);
+ if (pskb) {
+ pci_unmap_single(rtlpci->pdev,
+ rtlpriv->cfg->ops->get_desc(
+ (u8 *)entry, true, HW_DESC_TXBUFF_ADDR),
+ pskb->len, PCI_DMA_TODEVICE);
+ }

/*NB: the beacon data buffer must be 32-bit aligned. */
pskb = ieee80211_beacon_get(hw, mac->vif);

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