linux-kernel - Re: patch 46/47 causes NULL pointer deref on mt7921

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Message-ID: <62226273aaafafda1a4f3abc0f8c95220407b3a7.camel@web.de>
Date: Mon, 12 Aug 2024 10:57:31 +0200
From: Bert Karwatzki <spasswolf@....de>
To: Kalle Valo <kvalo@...nel.org>
Cc: Felix Fietkau <nbd@....name>, Sean Wang <sean.wang@...nel.org>, 
	deren.wu@...iatek.com, linux-mediatek@...ts.infradead.org, 
	linux-wireless@...r.kernel.org, lorenzo.bianconi@...hat.com, 
	mingyen.hsieh@...iatek.com, sean.wang@...iatek.com, spasswolf@....de, 
	linux-kernel@...r.kernel.org, deren.wu@...iatek.com
Subject: Re: patch 46/47 causes NULL pointer deref on mt7921

Am Dienstag, dem 06.08.2024 um 13:22 +0200 schrieb Bert Karwatzki:
> Am Mittwoch, dem 31.07.2024 um 11:51 +0300 schrieb Kalle Valo:
> > Bert Karwatzki <spasswolf@....de> writes:
> >
> > > Am Mittwoch, dem 17.07.2024 um 17:25 +0200 schrieb Felix Fietkau:
> > >
> > > > On 17.07.24 16:38, Bert Karwatzki wrote:
> > > >
> > > > > So mvif->phy can be NULL at the start of mt7921_ipv6_addr_change. The early
> > > > > return in that case avoids the NULL pointer and mvif->phy has its usual value
> > > > > again on the next call to mt7921_ipv6_addr_change so Wifi is working again. I
> > > > > don't know how this could happen but perhaps you have an idea.
> > > >
> > > > This change should fix it: https://nbd.name/p/0747f54f
> > > > Please test.
> > >
> > > The BUG is still present in linux-6.11-rc1.
> >
> > I'm not sure what's the status with this. There's one mt76 patch going
> > to v6.11-rc2:
> >
> > https://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless.git/commit/?id=6557a28f3e3a54cff4f0dcdd1dfa649b26557ab3
> >
> > But that looks to be a fix for a different problem, right? Felix, are
> > you planning to submit that 0747f54f as a proper patch? I could then
> > take it to wireless tree.
> >
> The Bug is still present in linux-6.11-rc2 and linux-next-20240806. Also the
> mvif->phy NULL check in the original patch is not neccessary (and feels a little
> out of place as mvif->phy is not needed anymore). This patch is sufficient to
> fix the NULL pointer dereference:
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/main.c
> b/drivers/net/wireless/mediatek/mt76/mt7921/main.c
> index 1bab93d049df..23b228804289 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7921/main.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7921/main.c
> @@ -1183,7 +1183,7 @@ static void mt7921_ipv6_addr_change(struct ieee80211_hw
> *hw,
>                                     struct inet6_dev *idev)
>  {
>         struct mt792x_vif *mvif = (struct mt792x_vif *)vif->drv_priv;
> -       struct mt792x_dev *dev = mvif->phy->dev;
> +       struct mt792x_dev *dev = mt792x_hw_dev(hw);
>         struct inet6_ifaddr *ifa;
>         struct in6_addr ns_addrs[IEEE80211_BSS_ARP_ADDR_LIST_LEN];
>         struct sk_buff *skb;
>
> Bert Karwatzki

This error is still present in v6.11-rc3.

Bert Karwatzki