From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5B981ECAAD3 for ; Mon, 19 Sep 2022 09:24:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230179AbiISJYk (ORCPT ); Mon, 19 Sep 2022 05:24:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34998 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230164AbiISJYb (ORCPT ); Mon, 19 Sep 2022 05:24:31 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DB9F1338 for ; Mon, 19 Sep 2022 02:24:27 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 516B1221E2; Mon, 19 Sep 2022 09:24:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1663579466; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ZbT40zAkjhP9+n399AbT5L2GEVohnR2lNfZdDMkmB2I=; b=s7BIrRKzRZ+RqyZh2vSJZm4djBMvyblnab40+wDxnhBKlf3MB4hBjij98pChd1+S+TzuRa MsteH+FOFgTLCu0kdyL0feWZ913GWoADpX0LuFj/yUQ150nRA+wZaxeF07l6ALfUhN2clr 6GA0quk9IMOYnSlX0qe6nUayb/9Jhfc= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1663579466; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ZbT40zAkjhP9+n399AbT5L2GEVohnR2lNfZdDMkmB2I=; b=0MM+F95WPpXuJsELVkK2StvHIAoYnMOAq3u+fUYU4cuiMs/GOJvupOr/SOIu/K66OB/2fD IpnycQVdVkOjC6Cg== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 2CEBE13A96; Mon, 19 Sep 2022 09:24:26 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id xO4ZCko1KGMTVAAAMHmgww (envelope-from ); Mon, 19 Sep 2022 09:24:26 +0000 Date: Mon, 19 Sep 2022 11:24:25 +0200 Message-ID: <87r107btti.wl-tiwai@suse.de> From: Takashi Iwai To: Rondreis Cc: perex@perex.cz, tiwai@suse.com, alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org Subject: Re: KASAN: invalid-free in snd_card_new In-Reply-To: <871qs7dav5.wl-tiwai@suse.de> References: <871qs7dav5.wl-tiwai@suse.de> User-Agent: Wanderlust/2.15.9 (Almost Unreal) Emacs/27.2 Mule/6.0 MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 19 Sep 2022 10:30:54 +0200, Takashi Iwai wrote: > > On Sun, 18 Sep 2022 15:01:11 +0200, > Rondreis wrote: > > > > Hello, > > > > When fuzzing the Linux kernel driver v6.0-rc4, the following crash was > > triggered. > > > > HEAD commit: 7e18e42e4b280c85b76967a9106a13ca61c16179 > > git tree: upstream > > > > kernel config: https://pastebin.com/raw/xtrgsXP3 > > C reproducer: https://pastebin.com/raw/w2sdQWYj > > console output: https://pastebin.com/raw/Yyf7zw2d > > > > Basically, in the c reproducer, we use the gadget module to emulate > > attaching a USB device(vendor id: 0x1bc7, product id: 0x1206, with the > > midi function) and executing some simple sequence of system calls. > > To reproduce this crash, we utilize a third-party library to emulate > > the attaching process: https://github.com/linux-usb-gadgets/libusbgx. > > Just clone this repository, install it, and compile the c > > reproducer with ``` gcc crash.c -lusbgx -lconfig -o crash ``` will do > > the trick. > > > > I would appreciate it if you have any idea how to solve this bug. > > Could you try the patch below? It looks like a simple double-free in > the code. A more proper patch is below. Please give it a try. thanks, Takashi -- 8< -- From: Takashi Iwai Subject: [PATCH] ALSA: core: Fix double-free at snd_card_new() During the code change to add the support for devres-managed card instance, we put an explicit kfree(card) call at the error path in snd_card_new(). This is needed for the early error path before the card is initialized with the device, but is rather superfluous and causes a double-free at the error path after the card instance is initialized, as the destructor of the card object already contains a kfree() call. This patch fixes the double-free situation by removing the superfluous kfree(). Meanwhile we need to call kfree() explicitly for the early error path, so it's added there instead. Fixes: e8ad415b7a55 ("ALSA: core: Add managed card creation") Reported-by: Rondreis Cc: Link: https://lore.kernel.org/r/CAB7eexL1zBnB636hwS27d-LdPYZ_R1-5fJS_h=ZbCWYU=UPWJg@mail.gmail.com Signed-off-by: Takashi Iwai --- sound/core/init.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/sound/core/init.c b/sound/core/init.c index 193dae361fac..5377f94eb211 100644 --- a/sound/core/init.c +++ b/sound/core/init.c @@ -178,10 +178,8 @@ int snd_card_new(struct device *parent, int idx, const char *xid, return -ENOMEM; err = snd_card_init(card, parent, idx, xid, module, extra_size); - if (err < 0) { - kfree(card); - return err; - } + if (err < 0) + return err; /* card is freed by error handler */ *card_ret = card; return 0; @@ -233,7 +231,7 @@ int snd_devm_card_new(struct device *parent, int idx, const char *xid, card->managed = true; err = snd_card_init(card, parent, idx, xid, module, extra_size); if (err < 0) { - devres_free(card); + devres_free(card); /* in managed mode, we need to free manually */ return err; } @@ -297,6 +295,8 @@ static int snd_card_init(struct snd_card *card, struct device *parent, mutex_unlock(&snd_card_mutex); dev_err(parent, "cannot find the slot for index %d (range 0-%i), error: %d\n", idx, snd_ecards_limit - 1, err); + if (!card->managed) + kfree(card); /* manually free here, as no destructor called */ return err; } set_bit(idx, snd_cards_lock); /* lock it */ -- 2.35.3