p54: Initialize extra_len in p54_tx_80211

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@googlemail.com>
Signed-off-by: Jason Conti <jason.conti@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

diff --git a/drivers/net/wireless/p54/txrx.c b/drivers/net/wireless/p54/txrx.c
index 9ad0f5f0c8844a49c0619f9e7467c6cd7798059c..7ef1e610d28e8497e042d4d4d2089936a8705918 100644 (file)
--- a/drivers/net/wireless/p54/txrx.c
+++ b/drivers/net/wireless/p54/txrx.c
@@ -702,7 +702,7 @@ 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;