Messages in this thread | | | From | Pkshih <> | Subject | RE: [PATCH][next] rtw89: Fix potential dereference of the null pointer sta | Date | Thu, 4 Nov 2021 01:38:44 +0000 |
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> -----Original Message----- > From: Dan Carpenter <dan.carpenter@oracle.com> > Sent: Wednesday, November 3, 2021 6:21 PM > To: Pkshih <pkshih@realtek.com> > Cc: Colin King <colin.king@canonical.com>; Kalle Valo <kvalo@codeaurora.org>; David S . Miller > <davem@davemloft.net>; Jakub Kicinski <kuba@kernel.org>; linux-wireless@vger.kernel.org; > netdev@vger.kernel.org; kernel-janitors@vger.kernel.org; linux-kernel@vger.kernel.org > Subject: Re: [PATCH][next] rtw89: Fix potential dereference of the null pointer sta > > On Wed, Nov 03, 2021 at 12:36:17AM +0000, Pkshih wrote: > > > > > > diff --git a/drivers/net/wireless/realtek/rtw89/core.c > > > > > b/drivers/net/wireless/realtek/rtw89/core.c > > > > > index 06fb6e5b1b37..26f52a25f545 100644 > > > > > --- a/drivers/net/wireless/realtek/rtw89/core.c > > > > > +++ b/drivers/net/wireless/realtek/rtw89/core.c > > > > > @@ -1534,9 +1534,14 @@ static bool rtw89_core_txq_agg_wait(struct rtw89_dev *rtwdev, > > > > > { > > > > > struct rtw89_txq *rtwtxq = (struct rtw89_txq *)txq->drv_priv; > > > > > struct ieee80211_sta *sta = txq->sta; > > > > > - struct rtw89_sta *rtwsta = (struct rtw89_sta *)sta->drv_priv; > > > > > > > > 'sta->drv_priv' is only a pointer, we don't really dereference the > > > > data right here, so I think this is safe. More, compiler can optimize > > > > this instruction that reorder it to the place just right before using. > > > > So, it seems like a false alarm. > > > > > > The warning is about "sta" not "sta->priv". It's not a false positive. > > > > > > I have heard discussions about compilers trying to work around these > > > bugs by re-ordering the code. Is that an option in GCC? It's not > > > something we should rely on, but I'm just curious if it exists in > > > released versions. > > > > > > > I say GCC does "reorder" the code, because the object codes of following > > two codes are identical with default or -Os ccflags. > > Huh... That's cool. GCC doesn't re-order it for me, but I'm on GCC 8 > so maybe it will work when I get to a more modern version. >
My GCC is 9.3.0. But, I don't try other versions.
-- Ping-Ke
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