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Date: Thu, 31 Oct 2013 18:48:35 -0700
From: Joe Perches <joe@...ches.com>
To: Ben Hutchings <bhutchings@...arflare.com>
Cc: Larry Finger <Larry.Finger@...inger.net>, linville@...driver.com,
linux-wireless@...r.kernel.org,
Mark Cave-Ayland <mark.cave-ayland@...nde.co.uk>,
netdev@...r.kernel.org, Stable <stable@...r.kernel.org>
Subject: Re: [PATCH NEXT V2] rtlwifi: Fix endian error in extracting packet
type
On Fri, 2013-11-01 at 01:02 +0000, Ben Hutchings wrote:
> On Thu, 2013-10-31 at 19:43 -0500, Larry Finger wrote:
> > From: Mark Cave-Ayland <mark.cave-ayland@...nde.co.uk>
> >
> > All of the rtlwifi drivers have an error in the routine that tests if
> > the data is "special". If it is, the subsequant transmission will be
> > at the lowest rate to enhance reliability. The 16-bit quantity is
> > big-endian, but was being extracted in native CPU mode. One of the
> > effects of this bug is to inhibit association under some conditions
> > as the TX rate is too high.
> >
> > A statement that would have made the code correct had been changed to
> > a comment. Rather than just reinstating that code, the fix here passes
> > sparse tests. A side effect of fixing this problem would have been to force
> > all IPv6 frames to run at the lowest rate. The test for that frame type
> > is removed.
> >
> > The original code only checked the lower-order byte of UDP ports for BOOTP
> > protocol. That is extended to the full 16-bit source and destination ports.
> >
> > One of the local headers contained duplicates of some of the ETH_P_XXX
> > definitions. These are deleted.
> >
> > Signed-off-by: Larry Finger <Larry.Finger@...inger.net>
> > Cc: Mark Cave-Ayland <mark.cave-ayland@...nde.co.uk>
> > Cc: Stable <stable@...r.kernel.org> [2.6.38+]
> > ---
> >
> > V2 - Addresses comments by Ben Hutchings and Bjorn Mork.
> >
> > drivers/net/wireless/rtlwifi/base.c | 15 ++++++---------
> > drivers/net/wireless/rtlwifi/wifi.h | 6 +-----
> > 2 files changed, 7 insertions(+), 14 deletions(-)
> > Index: wireless-testing-save/drivers/net/wireless/rtlwifi/base.c
> > ===================================================================
> > --- wireless-testing-save.orig/drivers/net/wireless/rtlwifi/base.c
> > +++ wireless-testing-save/drivers/net/wireless/rtlwifi/base.c
> > @@ -1077,17 +1077,17 @@ u8 rtl_is_special_data(struct ieee80211_
> >
> > ip = (struct iphdr *)((u8 *) skb->data + mac_hdr_len +
> > SNAP_SIZE + PROTOC_TYPE_SIZE);
> > - ether_type = *(u16 *) ((u8 *) skb->data + mac_hdr_len + SNAP_SIZE);
> > - /* ether_type = ntohs(ether_type); */
> > + ether_type = be16_to_cpu(*(__be16 *)((u8 *)skb->data + mac_hdr_len +
> > + SNAP_SIZE));
> >
> > if (ETH_P_IP == ether_type) {
> > if (IPPROTO_UDP == ip->protocol) {
> > struct udphdr *udp = (struct udphdr *)((u8 *) ip +
> > (ip->ihl << 2));
> > - if (((((u8 *) udp)[1] == 68) &&
> > - (((u8 *) udp)[3] == 67)) ||
> > - ((((u8 *) udp)[1] == 67) &&
> > - (((u8 *) udp)[3] == 68))) {
> > + if (((((u16 *) udp)[0] == 68) &&
> > + (((u16 *) udp)[2] == 67)) ||
> > + ((((u16 *) udp)[0] == 67) &&
> > + (((u16 *) udp)[2] == 68))) {
> [...]
>
> Now you're missing byte-swapping here, and using the wrong offset for
> the dest port (4 bytes rather than 2).
>
> If you really think this is necessary then use something like:
> if ((udp->source == htons(68) &&
> udp->dest == htons(67)) ||
> ...
Or maybe something like this?
---
drivers/net/wireless/rtlwifi/base.c | 91 +++++++++++++++++--------------------
1 file changed, 41 insertions(+), 50 deletions(-)
diff --git a/drivers/net/wireless/rtlwifi/base.c b/drivers/net/wireless/rtlwifi/base.c
index 9a78e3d..7e9df65 100644
--- a/drivers/net/wireless/rtlwifi/base.c
+++ b/drivers/net/wireless/rtlwifi/base.c
@@ -37,6 +37,7 @@
#include <linux/ip.h>
#include <linux/module.h>
+#include <linux/udp.h>
/*
*NOTICE!!!: This file will be very big, we should
@@ -1074,64 +1075,54 @@ u8 rtl_is_special_data(struct ieee80211_hw *hw, struct sk_buff *skb, u8 is_tx)
if (!ieee80211_is_data(fc))
return false;
+ ip = (const struct iphdr *)(skb->data + mac_hdr_len +
+ SNAP_SIZE + PROTOC_TYPE_SIZE);
+ ether_type = be16_to_cpup((__be16 *)
+ (skb->data + mac_hdr_len + SNAP_SIZE));
- ip = (struct iphdr *)((u8 *) skb->data + mac_hdr_len +
- SNAP_SIZE + PROTOC_TYPE_SIZE);
- ether_type = *(u16 *) ((u8 *) skb->data + mac_hdr_len + SNAP_SIZE);
- /* ether_type = ntohs(ether_type); */
-
- if (ETH_P_IP == ether_type) {
- if (IPPROTO_UDP == ip->protocol) {
- struct udphdr *udp = (struct udphdr *)((u8 *) ip +
- (ip->ihl << 2));
- if (((((u8 *) udp)[1] == 68) &&
- (((u8 *) udp)[3] == 67)) ||
- ((((u8 *) udp)[1] == 67) &&
- (((u8 *) udp)[3] == 68))) {
- /*
- * 68 : UDP BOOTP client
- * 67 : UDP BOOTP server
- */
- RT_TRACE(rtlpriv, (COMP_SEND | COMP_RECV),
- DBG_DMESG, "dhcp %s !!\n",
- is_tx ? "Tx" : "Rx");
-
- if (is_tx) {
- rtlpriv->enter_ps = false;
- schedule_work(&rtlpriv->
- works.lps_change_work);
- ppsc->last_delaylps_stamp_jiffies =
- jiffies;
- }
+ switch (ether_type) {
+ case ETH_P_IP: {
+ struct udphdr *udp;
+ u16 src;
+ u16 dst;
- return true;
- }
- }
- } else if (ETH_P_ARP == ether_type) {
- if (is_tx) {
- rtlpriv->enter_ps = false;
- schedule_work(&rtlpriv->works.lps_change_work);
- ppsc->last_delaylps_stamp_jiffies = jiffies;
- }
+ if (ip->protocol != IPPROTO_UDP)
+ return false;
- return true;
- } else if (ETH_P_PAE == ether_type) {
- RT_TRACE(rtlpriv, (COMP_SEND | COMP_RECV), DBG_DMESG,
- "802.1X %s EAPOL pkt!!\n", is_tx ? "Tx" : "Rx");
+ udp = (struct udphdr *)((u8 *)ip + (ip->ihl << 2));
+ src = be16_to_cpu(udp->source) >> 8;
+ dst = be16_to_cpu(udp->dest) >> 8;
- if (is_tx) {
- rtlpriv->enter_ps = false;
- schedule_work(&rtlpriv->works.lps_change_work);
- ppsc->last_delaylps_stamp_jiffies = jiffies;
- }
+ /*
+ * 68 : UDP BOOTP client
+ * 67 : UDP BOOTP server
+ */
+ if (!((src == 68 && dst == 67) || (src == 67 && dst == 68)))
+ return false;
+ RT_TRACE(rtlpriv, (COMP_SEND | COMP_RECV), DBG_DMESG,
+ "dhcp %s !!\n", is_tx ? "Tx" : "Rx");
+ break;
+ }
+ case ETH_P_ARP:
+ break;
+ case ETH_P_PAE:
+ RT_TRACE(rtlpriv, (COMP_SEND | COMP_RECV), DBG_DMESG,
+ "802.1X %s EAPOL pkt!!\n", is_tx ? "Tx" : "Rx");
+ break;
+ case ETH_P_IPV6:
return true;
- } else if (ETH_P_IPV6 == ether_type) {
- /* IPv6 */
- return true;
+ default:
+ return false;
}
- return false;
+ if (is_tx) {
+ rtlpriv->enter_ps = false;
+ schedule_work(&rtlpriv->works.lps_change_work);
+ ppsc->last_delaylps_stamp_jiffies = jiffies;
+ }
+
+ return true;
}
EXPORT_SYMBOL_GPL(rtl_is_special_data);
--
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