Messages in this thread | | | Date | Mon, 12 Mar 2012 10:06:23 +0530 | From | Mohammed Shafi Shajakhan <> | Subject | Re: [ 08/12] mac80211: zero initialize count field in ieee80211_tx_rate |
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Hi Ben,
On Monday 12 March 2012 07:27 AM, Ben Hutchings wrote: > On Mon, 2012-03-12 at 01:20 +0100, Willy Tarreau wrote: >> 2.6.32-longterm review patch. If anyone has any objections, please let me know. >> >> ------------------ >> >> From: Mohammed Shafi Shajakhan<mohammed@qca.qualcomm.com> >> >> commit 8617b093d0031837a7be9b32bc674580cfb5f6b5 upstream. >> >> rate control algorithms concludes the rate as invalid >> with rate[i].idx< -1 , while they do also check for rate[i].count is >> non-zero. it would be safer to zero initialize the 'count' field. >> recently we had a ath9k rate control crash where the ath9k rate control >> in ath_tx_status assumed to check only for rate[i].count being non-zero >> in one instance and ended up in using invalid rate index for >> 'connection monitoring NULL func frames' which eventually lead to the crash. >> thanks to Pavel Roskin for fixing it and finding the root cause. >> https://bugzilla.redhat.com/show_bug.cgi?id=768639 > > In 2.6.32, ath_tx_status() checks that rates[i].idx>= 0, so it properly > ignores these dummy entries. Further, there is code further down the > rate_control_get_rate() function that sets .idx only and appears to > depend on the initialisation of .count = 1. > > So I'm pretty sure this patch is wrong for 2.6.32; it could be > backported but I don't think the change is necessary anyway.
true, but i think its better to initialize the count = 0 rather than count = 1, though the older version driver checks for rate[i].idx >= 0 in ath_rc_tx_status. while the ath_tx_status has no such iteration in the older driver code.
> > Ben. > >> Cc: stable@vger.kernel.org >> Cc: Pavel Roskin<proski@gnu.org> >> Signed-off-by: Mohammed Shafi Shajakhan<mohammed@qca.qualcomm.com> >> Signed-off-by: John W. Linville<linville@tuxdriver.com> >> >> diff --git a/net/mac80211/rate.c b/net/mac80211/rate.c >> index ad64f4d..f9b8e81 100644 >> --- a/net/mac80211/rate.c >> +++ b/net/mac80211/rate.c >> @@ -344,7 +344,7 @@ void rate_control_get_rate(struct ieee80211_sub_if_data *sdata, >> for (i = 0; i< IEEE80211_TX_MAX_RATES; i++) { >> info->control.rates[i].idx = -1; >> info->control.rates[i].flags = 0; >> - info->control.rates[i].count = 1; >> + info->control.rates[i].count = 0; >> } >> >> if (sdata->local->hw.flags& IEEE80211_HW_HAS_RATE_CONTROL) >> >> >> -- >> To unsubscribe from this list: send the line "unsubscribe stable" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >
-- thanks, shafi
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