From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 0A4AF38D01A for ; Mon, 20 Apr 2026 08:37:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776674258; cv=none; b=GNiWMF1ImtkIRh+za0zOdlpqPovps4gR+PrrV+2YHCnYIgYqGn5fyBjQZmKIEIdpz73u1rxkrQ1qdifWE5y3XIj0z6gCfsmQi0a+apOEmANq8YIIfvWPz+vFlXoTHHJPgDSgb4tXY3YLU873l+xwF0AVN5OS0X5AnnucjF2AMpU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776674258; c=relaxed/simple; bh=Mueh1+AhgGs/BauhuJNGcBUyo52NSt02ZynYIE1e/os=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SkyejPlKgVi0RGZyMqPIgo7pN7G/a4VLo1vvotnLmP2XvknrkKVyBALPklnzKD73wqw9Apf/63kV2p+sQROgcZhiHxEAt2jqbaLwNgdUVLNrpUAWKVvepkk+/LilCSSmiT3FwdEQZNEta1ThOycBqVnGbCFgKeIbDi4hlxxpyUg= 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=W4BHB2RD; arc=none smtp.client-ip=170.10.129.124 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="W4BHB2RD" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1776674256; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RxAt8h3Z5s//UgNA1V43SWKyEAFpFt5qMrF31FeEFDE=; b=W4BHB2RD2e6FO2caVljvNFPhVBTvG7oBavwqe+Yg+oL1065mrIS4sePF2Y1cqFect5Eyte e+UFroh8OydVABvrse0x011VrYUpQQLxqnu9JQG+k206dalugviv2fvFhisQjW3NgfWWm9 nUtBD0DBHlf5rHTpKFqr1LLYiBNtwBg= 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-201-x4HYGNN4MX-KuWrsWdkrPA-1; Mon, 20 Apr 2026 04:37:33 -0400 X-MC-Unique: x4HYGNN4MX-KuWrsWdkrPA-1 X-Mimecast-MFC-AGG-ID: x4HYGNN4MX-KuWrsWdkrPA_1776674251 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (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 960F21956065; Mon, 20 Apr 2026 08:37:30 +0000 (UTC) Received: from warthog.procyon.org.com (unknown [10.44.48.17]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 7AB033000C15; Mon, 20 Apr 2026 08:37:26 +0000 (UTC) From: David Howells To: Christian Brauner Cc: David Howells , Paulo Alcantara , netfs@lists.linux.dev, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Viacheslav Dubeyko , Matthew Wilcox Subject: [PATCH 03/11] netfs: Fix potential UAF in netfs_unlock_abandoned_read_pages() Date: Mon, 20 Apr 2026 09:36:54 +0100 Message-ID: <20260420083705.1009074-4-dhowells@redhat.com> In-Reply-To: <20260420083705.1009074-1-dhowells@redhat.com> References: <20260420083705.1009074-1-dhowells@redhat.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 netfs_unlock_abandoned_read_pages(rreq) accesses the index of the folios it is wanting to unlock and compares that to rreq->no_unlock_folio so that it doesn't unlock a folio being read for netfs_perform_write() or netfs_write_begin(). However, given that netfs_unlock_abandoned_read_pages() is called _after_ NETFS_RREQ_IN_PROGRESS is cleared, the one folio that it's not allowed to dereference is the one specified by ->no_unlock_folio as ownership immediately reverts to the caller. Fix this by storing the folio pointer instead and using that rather than the index. Also fix netfs_unlock_read_folio() where the same applies. Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading") Closes: https://sashiko.dev/#/patchset/20260414082004.3756080-1-dhowells%40redhat.com Signed-off-by: David Howells cc: Paulo Alcantara cc: Viacheslav Dubeyko cc: Matthew Wilcox cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org --- fs/netfs/buffered_read.c | 4 ++-- fs/netfs/read_collect.c | 2 +- fs/netfs/read_retry.c | 2 +- include/linux/netfs.h | 2 +- 4 files changed, 5 insertions(+), 5 deletions(-) diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c index 51caad535438..b4d271538f75 100644 --- a/fs/netfs/buffered_read.c +++ b/fs/netfs/buffered_read.c @@ -670,7 +670,7 @@ int netfs_write_begin(struct netfs_inode *ctx, ret = PTR_ERR(rreq); goto error; } - rreq->no_unlock_folio = folio->index; + rreq->no_unlock_folio = folio; __set_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags); ret = netfs_begin_cache_read(rreq, ctx); @@ -736,7 +736,7 @@ int netfs_prefetch_for_write(struct file *file, struct folio *folio, goto error; } - rreq->no_unlock_folio = folio->index; + rreq->no_unlock_folio = folio; __set_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags); ret = netfs_begin_cache_read(rreq, ctx); if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS) diff --git a/fs/netfs/read_collect.c b/fs/netfs/read_collect.c index e5f6665b3341..eae067e3eaa5 100644 --- a/fs/netfs/read_collect.c +++ b/fs/netfs/read_collect.c @@ -83,7 +83,7 @@ static void netfs_unlock_read_folio(struct netfs_io_request *rreq, } just_unlock: - if (folio->index == rreq->no_unlock_folio && + if (folio == rreq->no_unlock_folio && test_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags)) { _debug("no unlock"); } else { diff --git a/fs/netfs/read_retry.c b/fs/netfs/read_retry.c index 68fc869513ef..999177426141 100644 --- a/fs/netfs/read_retry.c +++ b/fs/netfs/read_retry.c @@ -288,7 +288,7 @@ void netfs_unlock_abandoned_read_pages(struct netfs_io_request *rreq) struct folio *folio = folioq_folio(p, slot); if (folio && !folioq_is_marked2(p, slot)) { - if (folio->index == rreq->no_unlock_folio && + if (folio == rreq->no_unlock_folio && test_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags)) { _debug("no unlock"); diff --git a/include/linux/netfs.h b/include/linux/netfs.h index ba17ac5bf356..62a528f90666 100644 --- a/include/linux/netfs.h +++ b/include/linux/netfs.h @@ -252,7 +252,7 @@ struct netfs_io_request { unsigned long long collected_to; /* Point we've collected to */ unsigned long long cleaned_to; /* Position we've cleaned folios to */ unsigned long long abandon_to; /* Position to abandon folios to */ - pgoff_t no_unlock_folio; /* Don't unlock this folio after read */ + const struct folio *no_unlock_folio; /* Don't unlock this folio after read */ unsigned int direct_bv_count; /* Number of elements in direct_bv[] */ unsigned int debug_id; unsigned int rsize; /* Maximum read size (0 for none) */