{"id":2223486,"url":"http://patchwork.ozlabs.org/api/1.2/patches/2223486/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-cifs-client/patch/261128.1776251770@warthog.procyon.org.uk/","project":{"id":12,"url":"http://patchwork.ozlabs.org/api/1.2/projects/12/?format=json","name":"Linux CIFS Client","link_name":"linux-cifs-client","list_id":"linux-cifs.vger.kernel.org","list_email":"linux-cifs@vger.kernel.org","web_url":"","scm_url":"","webscm_url":"","list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<261128.1776251770@warthog.procyon.org.uk>","list_archive_url":null,"date":"2026-04-15T11:16:10","name":"netfs: Fix early put of sink folio in netfs_read_gaps()","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"02b4ca22d894b95b7d7d73fc5db8e868bda1aaae","submitter":{"id":59,"url":"http://patchwork.ozlabs.org/api/1.2/people/59/?format=json","name":"David Howells","email":"dhowells@redhat.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linux-cifs-client/patch/261128.1776251770@warthog.procyon.org.uk/mbox/","series":[{"id":499973,"url":"http://patchwork.ozlabs.org/api/1.2/series/499973/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-cifs-client/list/?series=499973","date":"2026-04-15T11:16:10","name":"netfs: Fix early put of sink folio in netfs_read_gaps()","version":1,"mbox":"http://patchwork.ozlabs.org/series/499973/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2223486/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2223486/checks/","tags":{},"related":[],"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-cifs@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 header.b=BeFL/R0f;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c04:e001:36c::12fc:5321; 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d=redhat.com;\n\ts=mimecast20190719; t=1776251783;\n\th=from:from:reply-to:subject:subject:date:date:message-id:message-id:\n\t to:to:cc:cc:mime-version:mime-version:content-type:content-type:\n\t content-transfer-encoding:content-transfer-encoding;\n\tbh=3dqApsnM+P4o09la4I1Tw9Wr5v2SnstRKsAAQ27vRWE=;\n\tb=BeFL/R0fUR92eacC0DWZWUZRu75I3o3/0tk7K9R2Mn987Nmj+pmsWQpTgwdCXv4uf2uWys\n\t0opQHeCjI507g465j+/ZjcrmF49UaHkwz0B1AlaGhRwomAiToJDMK68BsSAvFm1WRsQChj\n\tgL7Pwb29YDaQ0Z9TChgAvqqFe3D9Ubg=","X-MC-Unique":"N87LYPymM8CIPtI7ZtY8Gw-1","X-Mimecast-MFC-AGG-ID":"N87LYPymM8CIPtI7ZtY8Gw_1776251777","Organization":"Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley\n\tPlace, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United\n\tKingdom.\n\tRegistered in England and Wales under Company Registration No. 3798903","From":"David Howells ","To":"Christian Brauner ","Cc":"David Howells ,\n Paulo Alcantara , netfs@lists.linux.dev,\n linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org,\n ceph-devel@vger.kernel.org, linux-fsdevel@vger.kernel.org,\n linux-kernel@vger.kernel.org, Matthew Wilcox ","Subject":"[PATCH] netfs: Fix early put of sink folio in netfs_read_gaps()","Precedence":"bulk","X-Mailing-List":"linux-cifs@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","MIME-Version":"1.0","Content-Type":"text/plain; charset=\"us-ascii\"","Content-ID":"<261127.1776251770.1@warthog.procyon.org.uk>","Content-Transfer-Encoding":"quoted-printable","Date":"Wed, 15 Apr 2026 12:16:10 +0100","Message-ID":"<261128.1776251770@warthog.procyon.org.uk>","X-Scanned-By":"MIMEDefang 3.4.1 on 10.30.177.93"},"content":"Fix netfs_read_gaps() to release the sink page it uses after waiting for\nthe request to complete. The way the sink page is used is that an\nITER_BVEC-class iterator is created that has the gaps from the target folio\nat either end, but has the sink page tiled over the middle so that a single\nread op can fill in both gaps.\n\nThe bug was found by KASAN detecting a UAF on the generic/075 xfstest in\nthe cifsd kernel thread that handles reception of data from the TCP socket:\n\n BUG: KASAN: use-after-free in _copy_to_iter+0x48a/0xa20\n Write of size 885 at addr ffff888107f92000 by task cifsd/1285\n CPU: 2 UID: 0 PID: 1285 Comm: cifsd Not tainted 7.0.0 #6 PREEMPT(lazy)\n Call Trace:\n dump_stack_lvl+0x5d/0x80\n print_report+0x17f/0x4f1\n kasan_report+0x100/0x1e0\n kasan_check_range+0x10f/0x1e0\n __asan_memcpy+0x3c/0x60\n _copy_to_iter+0x48a/0xa20\n __skb_datagram_iter+0x2c9/0x430\n skb_copy_datagram_iter+0x6e/0x160\n tcp_recvmsg_locked+0xce0/0x1130\n tcp_recvmsg+0xeb/0x300\n inet_recvmsg+0xcf/0x3a0\n sock_recvmsg+0xea/0x100\n cifs_readv_from_socket+0x3a6/0x4d0 [cifs]\n cifs_read_iter_from_socket+0xdd/0x130 [cifs]\n cifs_readv_receive+0xaad/0xb10 [cifs]\n cifs_demultiplex_thread+0x1148/0x1740 [cifs]\n kthread+0x1cf/0x210\n\nFixes: ee4cdf7ba857 (\"netfs: Speed up buffered reading\")\nReported-by: Steve French \nSigned-off-by: David Howells \ncc: Paulo Alcantara \ncc: Matthew Wilcox \ncc: netfs@lists.linux.dev\ncc: linux-fsdevel@vger.kernel.org\n---\n fs/netfs/buffered_read.c | 6 +++---\n 1 file changed, 3 insertions(+), 3 deletions(-)","diff":"diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c\nindex c23173a061e8..dc50690fdd44 100644\n--- a/fs/netfs/buffered_read.c\n+++ b/fs/netfs/buffered_read.c\n@@ -459,9 +459,6 @@ static int netfs_read_gaps(struct file *file, struct folio *folio)\n \n \tnetfs_read_to_pagecache(rreq, NULL);\n \n-\tif (sink)\n-\t\tfolio_put(sink);\n-\n \tret = netfs_wait_for_read(rreq);\n \tif (ret >= 0) {\n \t\tfolio_detach_private(folio);\n@@ -471,6 +468,9 @@ static int netfs_read_gaps(struct file *file, struct folio *folio)\n \t\tflush_dcache_folio(folio);\n \t\tfolio_mark_uptodate(folio);\n \t}\n+\n+\tif (sink)\n+\t\tfolio_put(sink);\n \tfolio_unlock(folio);\n \tnetfs_put_request(rreq, netfs_rreq_trace_put_return);\n \treturn ret < 0 ? ret : 0;\n","prefixes":[]}