From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from metis.whiteo.stw.pengutronix.de (metis.whiteo.stw.pengutronix.de [185.203.201.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A1A2C1C02 for ; Fri, 21 Jun 2024 09:07:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.203.201.7 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718960856; cv=none; b=ij3qgj/95YRkgO2ONyc16xmutlClJYw/zYt6Dt5IEiDsH0HavgbEshV4l0YWvCTKKY3NXLPOrJtHOiKQ4rBdxd3zh2kJjCdtKgR3PfrRFAVwWse0Jwn9nrLKOMO/tQDwSxHLJ4YW96+Bpot6syt4nEyBM0VYDias4PII/kPUaxo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718960856; c=relaxed/simple; bh=SgOaTcKG835gy60m4IjLp/H/2iKKSCvbSBekjHONJqw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=aR9S1z0QdET5mnalOcb4LIvwnNPEVsw/8VR9nZQTMspj7uxCkOTEIc5hwvA6I6Xh7bdh7XTjGVFD49Ur77JG7JEeqzhnTE5ufWKm6Owq95AhgIDat+MZk2UdU3TNCjSZvkqpPl+vQB9iNHXmFEB/N2Rpt+VcAgPWeqnsijZYSiE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de; spf=pass smtp.mailfrom=pengutronix.de; arc=none smtp.client-ip=185.203.201.7 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=pengutronix.de Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1sKaEy-0002kG-Pq; Fri, 21 Jun 2024 11:07:28 +0200 Received: from [2a0a:edc0:2:b01:1d::c5] (helo=pty.whiteo.stw.pengutronix.de) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1sKaEx-003uIs-RK; Fri, 21 Jun 2024 11:07:27 +0200 Received: from sha by pty.whiteo.stw.pengutronix.de with local (Exim 4.96) (envelope-from ) id 1sKaEx-006Jek-2N; Fri, 21 Jun 2024 11:07:27 +0200 Date: Fri, 21 Jun 2024 11:07:27 +0200 From: Sascha Hauer To: Brian Norris Cc: Kalle Valo , linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, David Lin , Francesco Dolcini Subject: Re: [PATCH] [RFC] mwifiex: Fix NULL pointer deref Message-ID: References: <20240619070824.537856-1-s.hauer@pengutronix.de> <87wmmll5mf.fsf@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-SA-Exim-Connect-IP: 2a0a:edc0:0:c01:1d::a2 X-SA-Exim-Mail-From: sha@pengutronix.de X-SA-Exim-Scanned: No (on metis.whiteo.stw.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org On Thu, Jun 20, 2024 at 12:48:01PM -0700, Brian Norris wrote: > Hi Sascha, > > On Wed, Jun 19, 2024 at 11:05:28AM +0300, Kalle Valo wrote: > > Sascha Hauer writes: > > > > > When an Access Point is repeatedly started it happens that the > > > interrupts handler is called with priv->wdev.wiphy being NULL, but > > > dereferenced in mwifiex_parse_single_response_buf() resulting in: > > > > > > | Unable to handle kernel NULL pointer dereference at virtual address 0000000000000140 > ... > > > | pc : mwifiex_get_cfp+0xd8/0x15c [mwifiex] > > > | lr : mwifiex_get_cfp+0x34/0x15c [mwifiex] > > > | sp : ffff8000818b3a70 > > > | x29: ffff8000818b3a70 x28: ffff000006bfd8a5 x27: 0000000000000004 > > > | x26: 000000000000002c x25: 0000000000001511 x24: 0000000002e86bc9 > > > | x23: ffff000006bfd996 x22: 0000000000000004 x21: ffff000007bec000 > > > | x20: 000000000000002c x19: 0000000000000000 x18: 0000000000000000 > > > | x17: 000000040044ffff x16: 00500072b5503510 x15: ccc283740681e517 > > > | x14: 0201000101006d15 x13: 0000000002e8ff43 x12: 002c01000000ffb1 > > > | x11: 0100000000000000 x10: 02e8ff43002c0100 x9 : 0000ffb100100157 > > > | x8 : ffff000003d20000 x7 : 00000000000002f1 x6 : 00000000ffffe124 > > > | x5 : 0000000000000001 x4 : 0000000000000003 x3 : 0000000000000000 > > > | x2 : 0000000000000000 x1 : 0001000000011001 x0 : 0000000000000000 > > > | Call trace: > > > | mwifiex_get_cfp+0xd8/0x15c [mwifiex] > > > | mwifiex_parse_single_response_buf+0x1d0/0x504 [mwifiex] > > > | mwifiex_handle_event_ext_scan_report+0x19c/0x2f8 [mwifiex] > > > | mwifiex_process_sta_event+0x298/0xf0c [mwifiex] > > > | mwifiex_process_event+0x110/0x238 [mwifiex] > > > | mwifiex_main_process+0x428/0xa44 [mwifiex] > > > | mwifiex_sdio_interrupt+0x64/0x12c [mwifiex_sdio] > > > | process_sdio_pending_irqs+0x64/0x1b8 > > > | sdio_irq_work+0x4c/0x7c > > > | process_one_work+0x148/0x2a0 > > > | worker_thread+0x2fc/0x40c > > > | kthread+0x110/0x114 > > > | ret_from_fork+0x10/0x20 > > > | Code: a94153f3 a8c37bfd d50323bf d65f03c0 (f940a000) > > > | ---[ end trace 0000000000000000 ]--- > > > > > > Fix this by adding a NULL check before dereferencing this pointer. > > > > > > Signed-off-by: Sascha Hauer > > > > > > --- > > > > > > This is the most obvious fix for this problem, but I am not sure if we > > > might want to catch priv->wdev.wiphy being NULL earlier in the call > > > chain. > > > > I haven't looked at the call but the symptoms sound like that either we > > are enabling the interrupts too early or there's some kind of locking > > problem so that an other cpu doesn't see the change. > > I agree with Kalle that there's a different underlying bug involved, and > (my conclusion:) we shouldn't whack-a-mole the NULL pointer without > addressing the underlying problem. > > Looking a bit closer (and without much other context to go on): I believe > that one potential underlying problem is the complete lack of locking > between cfg80211 entry points (such as mwifiex_add_virtual_intf() or > mwifiex_cfg80211_change_virtual_intf()) and most stuff in the main loop > (mwifiex_main_process()). The former call sites only hold the wiphy > lock, and the latter tends to ... mostly not hold any locks, but rely on > sequentialization with itself, and using its |main_proc_lock| for setup > and teardown. It's all really bad and ready to fall down like a house of > cards at any moment. Unfortunately, no one has spent time on > rearchitecting this driver. > > So it's possible that mwifiex_process_event() (mwifiex_get_priv_by_id() > / mwifiex_get_priv()) is getting a hold of a not-fully-initialized > 'priv' structure. > > BTW, in case I can reproduce and poke at your scenario, what exactly > is your test case? Are you just starting / killing / restarting hostapd > in a loop? I am running plain wpa_supplicant -i mlan0 with this config: network={ ssid="somessid" mode=2 frequency=2412 key_mgmt=WPA-PSK WPA-PSK-SHA256 proto=RSN group=CCMP pairwise=CCMP psk="12345678" } wait for the AP to be established, wpa_supplicant and start it again. It doesn't seem to be a locking problem, see the patch below which fixes my problem. At some point during incoming events the correct adapter->priv[] is selected based on bss_num and bss_type. when adapter->priv[0] is used for AP mode then an incoming event with type MWIFIEX_BSS_TYPE_STA leads to adapter->priv[1] being picked which is unused and doesn't have a wiphy attached to it. Sascha -------------------------8<---------------------------- >From 3357963821294ff7de26259a154a1cb5bab760cb Mon Sep 17 00:00:00 2001 From: Sascha Hauer Date: Tue, 18 Jun 2024 12:20:20 +0200 Subject: [PATCH] mwifiex: Do not return unused priv in mwifiex_get_priv_by_id() mwifiex_get_priv_by_id() returns the priv pointer corresponding to the bss_num and bss_type, but without checking if the priv is actually currently in use. Unused priv pointers do not have a wiphy attached to them which can lead to NULL pointer dereferences further down the callstack. Fix this by returning only used priv pointers which have priv->bss_mode set to something else than NL80211_IFTYPE_UNSPECIFIED. Signed-off-by: Sascha Hauer --- drivers/net/wireless/marvell/mwifiex/main.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/net/wireless/marvell/mwifiex/main.h b/drivers/net/wireless/marvell/mwifiex/main.h index 175882485a195..c5164ae41b547 100644 --- a/drivers/net/wireless/marvell/mwifiex/main.h +++ b/drivers/net/wireless/marvell/mwifiex/main.h @@ -1287,6 +1287,9 @@ mwifiex_get_priv_by_id(struct mwifiex_adapter *adapter, for (i = 0; i < adapter->priv_num; i++) { if (adapter->priv[i]) { + if (adapter->priv[i]->bss_mode == NL80211_IFTYPE_UNSPECIFIED) + continue; + if ((adapter->priv[i]->bss_num == bss_num) && (adapter->priv[i]->bss_type == bss_type)) break; -- 2.39.2 -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |