From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 1615A2E7F25; Thu, 28 May 2026 20:41:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780000871; cv=none; b=OxMnC5CBSenFQTwXCiNo8CNMkthhzXH/l6RSFwg/Fk1YjeX/eMsq44Qh2yHTwryCNJIdsSlG3/eydhq0GMZNjiFKw/sE9Mx7eoa0nfxPU63KlV7YT8BRHGd+EJVOC/3Y62/JUbH1Xqbgb5o3+ho1GK2rN0Ff0W6hJmArLzJLVK4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780000871; c=relaxed/simple; bh=4FXsmHgIoevlN42nyRD5C/Fyc5uMenT6fj+TXTLKCro=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iCCZVnZL4MXiUa8fgC5nWYw8JSEDZJG1yzQKGIdwt294PqKWJ0+LpvKAdj3l1y267R+nca3QUUALjU2c2xdQ0m7s1uQYM9cXcc1lZkO7W6VR1vp/1QSZElwM8TG8tqwWtVUTsLQjxQ1woLM3Woexz+0ASCL882uSM9n/TztcvRc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Uch5u3Z5; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Uch5u3Z5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7B3781F00A3A; Thu, 28 May 2026 20:41:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1780000870; bh=E0z8vpZBAkikLUK7D8Amg49hNOwYTLBOeTpTNWxiFVQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Uch5u3Z5XVV+GnilQ9r34+EL/S5EX8PMHzTO7V8q4h1mI2d3cnv2BXwMSlV0aKV38 gT8ydjdL7Mhm0qNiYdEUr8vhjHgwHOhldYDtNGEL+kdrxX8KlWOZmMZvb5Szt9PUp6 cCvjogXw9taJc41hAESnFk9kzZVutrQ9hD9/25Q0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Steve French , David Howells , "Paulo Alcantara (Red Hat)" , Matthew Wilcox , netfs@lists.linux.dev, linux-fsdevel@vger.kernel.org, Christian Brauner , Sasha Levin Subject: [PATCH 6.12 197/272] netfs: Fix early put of sink folio in netfs_read_gaps() Date: Thu, 28 May 2026 21:49:31 +0200 Message-ID: <20260528194634.776862235@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260528194629.379955525@linuxfoundation.org> References: <20260528194629.379955525@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Howells [ Upstream commit 3e5dd91b87a8b1450217b56a336bee315f40da7d ] Fix netfs_read_gaps() to release the sink page it uses after waiting for the request to complete. The way the sink page is used is that an ITER_BVEC-class iterator is created that has the gaps from the target folio at either end, but has the sink page tiled over the middle so that a single read op can fill in both gaps. The bug was found by KASAN detecting a UAF on the generic/075 xfstest in the cifsd kernel thread that handles reception of data from the TCP socket: BUG: KASAN: use-after-free in _copy_to_iter+0x48a/0xa20 Write of size 885 at addr ffff888107f92000 by task cifsd/1285 CPU: 2 UID: 0 PID: 1285 Comm: cifsd Not tainted 7.0.0 #6 PREEMPT(lazy) Call Trace: dump_stack_lvl+0x5d/0x80 print_report+0x17f/0x4f1 kasan_report+0x100/0x1e0 kasan_check_range+0x10f/0x1e0 __asan_memcpy+0x3c/0x60 _copy_to_iter+0x48a/0xa20 __skb_datagram_iter+0x2c9/0x430 skb_copy_datagram_iter+0x6e/0x160 tcp_recvmsg_locked+0xce0/0x1130 tcp_recvmsg+0xeb/0x300 inet_recvmsg+0xcf/0x3a0 sock_recvmsg+0xea/0x100 cifs_readv_from_socket+0x3a6/0x4d0 [cifs] cifs_read_iter_from_socket+0xdd/0x130 [cifs] cifs_readv_receive+0xaad/0xb10 [cifs] cifs_demultiplex_thread+0x1148/0x1740 [cifs] kthread+0x1cf/0x210 Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading") Reported-by: Steve French Signed-off-by: David Howells Link: https://patch.msgid.link/20260512123404.719402-18-dhowells@redhat.com Reviewed-by: Paulo Alcantara (Red Hat) cc: Paulo Alcantara cc: Matthew Wilcox cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin --- fs/netfs/buffered_read.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c index 2dd2260352dbf..1c906035fef02 100644 --- a/fs/netfs/buffered_read.c +++ b/fs/netfs/buffered_read.c @@ -525,14 +525,14 @@ static int netfs_read_gaps(struct file *file, struct folio *folio) netfs_read_to_pagecache(rreq); - if (sink) - folio_put(sink); - ret = netfs_wait_for_read(rreq); if (ret == 0) { flush_dcache_folio(folio); folio_mark_uptodate(folio); } + + if (sink) + folio_put(sink); folio_unlock(folio); netfs_put_request(rreq, false, netfs_rreq_trace_put_return); return ret < 0 ? ret : 0; -- 2.53.0