[34-longterm 087/196] p54: Initialize extra_len in p54_tx_80211

[Paul Gortmaker]

From: Jason Conti <jason.conti@xxxxxxxxx>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
                   -------------------

commit a6756da9eace8b4af73e9dea43f1fc2889224c94 upstream.

This patch fixes a very serious off-by-one bug in
the driver, which could leave the device in an
unresponsive state.

The problem was that the extra_len variable [used to
reserve extra scratch buffer space for the firmware]
was left uninitialized. Because p54_assign_address
later needs the value to reserve additional space,
the resulting frame could be to big for the small
device's memory window and everything would
immediately come to a grinding halt.

Reference: https://bugs.launchpad.net/bugs/722185

Acked-by: Christian Lamparter <chunkeey@xxxxxxxxxxxxxx>
Signed-off-by: Jason Conti <jason.conti@xxxxxxxxx>
Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 drivers/net/wireless/p54/txrx.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/p54/txrx.c b/drivers/net/wireless/p54/txrx.c
index db89d65..8db2132 100644
--- a/drivers/net/wireless/p54/txrx.c
+++ b/drivers/net/wireless/p54/txrx.c
@@ -703,7 +703,7 @@ int p54_tx_80211(struct ieee80211_hw *dev, struct sk_buff *skb)
 	struct p54_tx_info *p54info;
 	struct p54_hdr *hdr;
 	struct p54_tx_data *txhdr;
-	unsigned int padding, len, extra_len;
+	unsigned int padding, len, extra_len = 0;
 	int i, j, ridx;
 	u16 hdr_flags = 0, aid = 0;
 	u8 rate, queue = 0, crypt_offset = 0;
-- 
1.7.9.3

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