From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 D2F472ECD1D for ; Wed, 24 Jun 2026 07:36:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782286611; cv=none; b=BouKPZTPRLzPhm6hMUBEOpSUOB+GSDO6SMRLLdJHPHfDE2Na+znBV/Qo023t+ti0ZCp3ABOzpLi4qHXfETg5t1EFNG3UlLgQ3/3xdBe17nhk91UIQmCU6E8y7OBWGEi8YKBtJ1FKDPGs/rWOP3zrVOqHb/EtxuFbOyJvzKwKnb4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782286611; c=relaxed/simple; bh=xJmPYeKRZ5FA4MxcGK7f/XLGX2YSXtBuBahifySUxQ4=; h=In-Reply-To:References:To:Cc:Subject:MIME-Version:Content-Type: From:Date:Message-ID; b=sqejGv8VlC9yZkpRcGd4o6SksYwvw2NFqx08d6u2KIrXAr+tLM8ZVX3Og6H1BZ0M6TqzxU2lrI/UwNYBj1wd3drUMji03UA4UVdalusCm5hf8D6TgHDtt77ge5FfYyxlyekEeA0XVICNQwVyETv8unFQyMS9wvHBGeMXlw0CS4k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=BqxV8Ajo; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="BqxV8Ajo" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1782286606; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=AzTq/JBODoLiXp9HIjZkxgqEFl68srXX6njhfZeyXrA=; b=BqxV8Ajok5m2JasrnSIHqg67ee0AfCaNpU2Tue5suR4SKj5NbvFj6S6horqdIyHDRM6Jby i3gtc0nWjfIHLne9BufMPeXQTv/yHzxbPc2LWrVUXOq7B679puSrXGraV9mr/6ZLBpjYa+ Mk0f0GbMHjnnw060xGCnZ3t3Tw1YOl8= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-592-7Mtza7J_M7qMK-Ndaan5tg-1; Wed, 24 Jun 2026 03:36:45 -0400 X-MC-Unique: 7Mtza7J_M7qMK-Ndaan5tg-1 X-Mimecast-MFC-AGG-ID: 7Mtza7J_M7qMK-Ndaan5tg_1782286603 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 31FA31956052; Wed, 24 Jun 2026 07:36:43 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.44.49.152]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 832551800591; Wed, 24 Jun 2026 07:36:39 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 In-Reply-To: <498534d3-e82e-40ce-bc7d-230580b2fcae@chenxiaosong.com> References: <498534d3-e82e-40ce-bc7d-230580b2fcae@chenxiaosong.com> <33cc8eb4-8831-49b0-80d6-b06544a37920@chenxiaosong.com> <2912807.1782231053@warthog.procyon.org.uk> To: ChenXiaoSong Cc: dhowells@redhat.com, hongao , Paulo Alcantara , netfs@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+3c74b1f0c372e98efc32@syzkaller.appspotmail.com, Steve French , Namjae Jeon , "linux-cifs@vger.kernel.org" Subject: Re: [PATCH] netfs: Fix UAF in netfs_unbuffered_write() on failed preparation Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <2939568.1782286565.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable From: David Howells Date: Wed, 24 Jun 2026 08:36:38 +0100 Message-ID: <2939650.1782286598@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 This excerpt would seem to show how the problem comes about: a.out-717 : netfs_sreq: R=3D00000001[13] UPLD PREP f=3D000 s=3D240000 0= /0 s=3D192 e=3D0 a.out-717 : netfs_sreq: R=3D00000001[13] UPLD SUBMT f=3D100 s=3D240000 0= /20000 s=3D192 e=3D0 a.out-717 : netfs_sreq: R=3D00000001[13] UPLD TERM f=3D310 s=3D240000 1= fac0/20000 s=3D160 e=3D0 a.out-717 : netfs_rreq: R=3D00000001 UW WAKE-Q f=3D1801 a.out-717 : netfs_rreq: R=3D00000001 UW DONE-QUIESCE f=3D1801 a.out-717 : netfs_sreq: R=3D00000001[13] UPLD RETRY f=3D210 s=3D240000 1= fac0/20000 s=3D160 e=3D-11 a.out-717 : netfs_sreq: R=3D00000001[13] UPLD SUBMT f=3D100 s=3D240000 0= /dbfac0 s=3D192 e=3D0 a.out-717 : netfs_failure: R=3D00000001[13] UPLD f=3D500 s=3D240000 0/db= fac0 write e=3D-5 It looks like there are two issues: firstly, why does the upload stop shor= t? Presumably that's forced by the test. Secondly, I think it has miscalcula= ted the subreq size in the retry, hence the EIO. David