Messages in this thread Patch in this message | | | Date | Mon, 6 Feb 2012 17:57:02 -0500 | From | Pavel Roskin <> | Subject | Re: [ath9k-devel] [3.3-rc2+] Thousands of ath9k warnings on dmesg before laptop froze |
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On Mon, 6 Feb 2012 00:29:07 +0000 "Carlos R. Mafra" <crmafra@gmail.com> wrote:
> > I'm testing the latest kernel 3.3.0-rc2+ I pulled from git > this morning. > > My laptop just froze, and when I rebooted I noticed > that /var/log/messages contained 48 thousand (!) warnings coming from > ath9k since a few hours ago. I'm pasting the first one:
> > ------------[ cut here ]------------ > WARNING: > at /home/mafra/linux-2.6/drivers/net/wireless/ath/ath9k/rc.c:697 > ath_rc_get_highest_rix+0x156/0x210 [ath9k]() Hardware name: VPCEB4X1E
I believe I found a solution for this today. Please see this bug tracker: https://bugzilla.redhat.com/show_bug.cgi?id=768639
While Fedora users report a warning, I've seen panic reports in the list. It's a memory corruption bug, so it can manifest in different ways. Please test the latest patch (attached).
Here's my comment to the patch:
This patch is based on my analysis of printk() output I added to the ath9k driver. I didn't have a chance to test the patch, so testing would be greatly appreciated.
The corruption must be happening in ath_debug_stat_rc(), which is given the result of ath_rc_get_rateindex(). ath_rc_get_rateindex() can return -1, which causes ath_debug_stat_rc() to increment the value that lies 16 bytes before rcstats in struct ath_rate_priv. On 64-bit systems, that happens to be rate_table. Once the rate_table pointer is incremented, all data there becomes invalid, which leads to the warning. On 32-bit systems, the corruption should happen in neg_ht_rates.
The -1 value of idx in struct ieee80211_tx_rate is described in net/mac80211.h. I don't know why we have -1 there and how to reproduce the problem reliably. But -1 can be there and ath9k has no checks for it.
The patch introduces two protections: ath_rc_get_rateindex() never returns a negative value and ath_debug_stat_rc() checks the array bounds.
It may not be good enough for the kernel, but it may be good enough for Fedora.
-- Regards, Pavel Roskin Prevent memory corruption in ath9k rate control algorithm
From: Pavel Roskin <proski@gnu.org>
Check final_rate in ath_debug_stat_rc(). Don't return negative values from ath_rc_get_rateindex(), callers don't expect it.
Signed-off-by: Pavel Roskin <proski@gnu.org> ---
drivers/net/wireless/ath/ath9k/rc.c | 10 ++++++++++ 1 files changed, 10 insertions(+), 0 deletions(-)
diff --git a/drivers/net/wireless/ath/ath9k/rc.c b/drivers/net/wireless/ath/ath9k/rc.c index 635b592..afe22f4 100644 --- a/drivers/net/wireless/ath/ath9k/rc.c +++ b/drivers/net/wireless/ath/ath9k/rc.c @@ -385,6 +385,11 @@ static int ath_rc_get_rateindex(const struct ath_rate_table *rate_table, int rix = 0, i = 0; static const int mcs_rix_off[] = { 7, 15, 20, 21, 22, 23 }; + if (rate->idx < 0) { + printk(KERN_ERR "%s: rate->idx = %d\n", __func__, rate->idx); + return 0; + } + if (!(rate->flags & IEEE80211_TX_RC_MCS)) return rate->idx; @@ -1324,6 +1329,11 @@ static void ath_debug_stat_rc(struct ath_rate_priv *rc, int final_rate) { struct ath_rc_stats *stats; + if (final_rate < 0 || final_rate >= RATE_TABLE_SIZE) { + printk(KERN_ERR "%s: invalid final_rate: %d\n", __func__, + final_rate); + return; + } stats = &rc->rcstats[final_rate]; stats->success++; } | |