b43: Add DMA poisoning patches

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@15121 3c298f89-4303-0410-b956-a3cf2f4a3e73

1 files changed, 105 insertions, 0 deletions

diff --git a/package/mac80211/patches/510-b43-poison-rx-buffers.patch b/package/mac80211/patches/510-b43-poison-rx-buffers.patch
new file mode 100644
index 0000000000..c50df132c3
--- /dev/null
+++ b/package/mac80211/patches/510-b43-poison-rx-buffers.patch
@@ -0,0 +1,105 @@
+This patch adds poisoning and sanity checking to the RX DMA buffers.
+This is used for protection against buggy hardware/firmware that raises
+RX interrupts without doing an actual DMA transfer.
+
+This mechanism protects against rare "bad packets" (due to uninitialized skb data)
+and rare kernel crashes due to uninitialized RX headers.
+
+The poison is selected to not match on valid frames and to be cheap for checking.
+
+The poison check mechanism _might_ trigger incorrectly, if we are voluntarily
+receiving frames with bad PLCP headers. However, this is nonfatal, because the
+chance of such a match is basically zero and in case it happens it just results
+in dropping the packet.
+Bad-PLCP RX defaults to off, and you should leave it off unless you want to listen
+to the latest news broadcasted by your microwave oven.
+
+This patch also moves the initialization of the RX-header "length" field in front of
+the mapping of the DMA buffer. The CPU should not touch the buffer after we mapped it.
+
+Cc: stable@kernel.org
+Reported-by: Francesco Gringoli <francesco.gringoli@ing.unibs.it>
+Signed-off-by: Michael Buesch <mb@bu3sch.de>
+
+---
+
+Index: compat-wireless-2009-03-31/drivers/net/wireless/b43/dma.c
+===================================================================
+--- compat-wireless-2009-03-31.orig/drivers/net/wireless/b43/dma.c	2009-04-06 18:52:25.000000000 +0200
++++ compat-wireless-2009-03-31/drivers/net/wireless/b43/dma.c	2009-04-06 18:52:30.000000000 +0200
+@@ -555,11 +555,32 @@ address_error:
+ 	return 1;
+ }
+ 
++static bool b43_rx_buffer_is_poisoned(struct b43_dmaring *ring, struct sk_buff *skb)
++{
++	unsigned char *f = skb->data + ring->frameoffset;
++
++	return ((f[0] & f[1] & f[2] & f[3] & f[4] & f[5] & f[6] & f[7]) == 0xFF);
++}
++
++static void b43_poison_rx_buffer(struct b43_dmaring *ring, struct sk_buff *skb)
++{
++	struct b43_rxhdr_fw4 *rxhdr;
++	unsigned char *frame;
++
++	/* This poisons the RX buffer to detect DMA failures. */
++
++	rxhdr = (struct b43_rxhdr_fw4 *)(skb->data);
++	rxhdr->frame_len = 0;
++
++	B43_WARN_ON(ring->rx_buffersize < ring->frameoffset + sizeof(struct b43_plcp_hdr6) + 2);
++	frame = skb->data + ring->frameoffset;
++	memset(frame, 0xFF, sizeof(struct b43_plcp_hdr6) + 2 /* padding */);
++}
++
+ static int setup_rx_descbuffer(struct b43_dmaring *ring,
+ 			       struct b43_dmadesc_generic *desc,
+ 			       struct b43_dmadesc_meta *meta, gfp_t gfp_flags)
+ {
+-	struct b43_rxhdr_fw4 *rxhdr;
+ 	dma_addr_t dmaaddr;
+ 	struct sk_buff *skb;
+ 
+@@ -568,6 +589,7 @@ static int setup_rx_descbuffer(struct b4
+ 	skb = __dev_alloc_skb(ring->rx_buffersize, gfp_flags);
+ 	if (unlikely(!skb))
+ 		return -ENOMEM;
++	b43_poison_rx_buffer(ring, skb);
+ 	dmaaddr = map_descbuffer(ring, skb->data, ring->rx_buffersize, 0);
+ 	if (b43_dma_mapping_error(ring, dmaaddr, ring->rx_buffersize, 0)) {
+ 		/* ugh. try to realloc in zone_dma */
+@@ -578,6 +600,7 @@ static int setup_rx_descbuffer(struct b4
+ 		skb = __dev_alloc_skb(ring->rx_buffersize, gfp_flags);
+ 		if (unlikely(!skb))
+ 			return -ENOMEM;
++		b43_poison_rx_buffer(ring, skb);
+ 		dmaaddr = map_descbuffer(ring, skb->data,
+ 					 ring->rx_buffersize, 0);
+ 		if (b43_dma_mapping_error(ring, dmaaddr, ring->rx_buffersize, 0)) {
+@@ -592,9 +615,6 @@ static int setup_rx_descbuffer(struct b4
+ 	ring->ops->fill_descriptor(ring, desc, dmaaddr,
+ 				   ring->rx_buffersize, 0, 0, 0);
+ 
+-	rxhdr = (struct b43_rxhdr_fw4 *)(skb->data);
+-	rxhdr->frame_len = 0;
+-
+ 	return 0;
+ }
+ 
+@@ -1489,6 +1509,15 @@ static void dma_rx(struct b43_dmaring *r
+ 			goto drop;
+ 		}
+ 	}
++	if (unlikely(b43_rx_buffer_is_poisoned(ring, skb))) {
++		/* Something went wrong with the DMA.
++		 * The device did not touch the buffer and did not overwrite the poison. */
++		b43dbg(ring->dev->wl, "DMA RX: Dropping poisoned buffer.\n");
++		/* recycle the descriptor buffer. */
++		sync_descbuffer_for_device(ring, meta->dmaaddr,
++					   ring->rx_buffersize);
++		goto drop;
++	}
+ 	if (unlikely(len > ring->rx_buffersize)) {
+ 		/* The data did not fit into one descriptor buffer
+ 		 * and is split over multiple buffers.