!303 Automatically generate code patches with openeuler !138

From: @kuhnchen18
Reviewed-by: @imxcc
Signed-off-by: @imxcc

9pfs-Fully-restart-unreclaim-loop-CVE-2021-20181.patch

@@ -0,0 +1,80 @@
+From 31012acf8fcf51131d1553bc3e04176ae51e8228 Mon Sep 17 00:00:00 2001
+From: Greg Kurz <groug@kaod.org>
+Date: Tue, 8 Jun 2021 09:07:17 +0800
+Subject: [PATCH] 9pfs: Fully restart unreclaim loop (CVE-2021-20181)
+
+Fix CVE-2021-20181
+
+Depending on the client activity, the server can be asked to open a huge
+number of file descriptors and eventually hit RLIMIT_NOFILE. This is
+currently mitigated using a reclaim logic : the server closes the file
+descriptors of idle fids, based on the assumption that it will be able
+to re-open them later. This assumption doesn't hold of course if the
+client requests the file to be unlinked. In this case, we loop on the
+entire fid list and mark all related fids as unreclaimable (the reclaim
+logic will just ignore them) and, of course, we open or re-open their
+file descriptors if needed since we're about to unlink the file.
+
+This is the purpose of v9fs_mark_fids_unreclaim(). Since the actual
+opening of a file can cause the coroutine to yield, another client
+request could possibly add a new fid that we may want to mark as
+non-reclaimable as well. The loop is thus restarted if the re-open
+request was actually transmitted to the backend. This is achieved
+by keeping a reference on the first fid (head) before traversing
+the list.
+
+This is wrong in several ways:
+- a potential clunk request from the client could tear the first
+  fid down and cause the reference to be stale. This leads to a
+  use-after-free error that can be detected with ASAN, using a
+  custom 9p client
+- fids are added at the head of the list : restarting from the
+  previous head will always miss fids added by a some other
+  potential request
+
+All these problems could be avoided if fids were being added at the
+end of the list. This can be achieved with a QSIMPLEQ, but this is
+probably too much change for a bug fix. For now let's keep it
+simple and just restart the loop from the current head.
+
+Fixes: CVE-2021-20181
+Buglink: https://bugs.launchpad.net/qemu/+bug/1911666
+Reported-by: Zero Day Initiative <zdi-disclosures@trendmicro.com>
+Reviewed-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
+Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
+Message-Id: <161064025265.1838153.15185571283519390907.stgit@bahia.lan>
+Signed-off-by: Greg Kurz <groug@kaod.org>
+
+Signed-off-by: Jiajie Li <lijiajie11@huawei.com>
+---
+ hw/9pfs/9p.c | 6 +++---
+ 1 file changed, 3 insertions(+), 3 deletions(-)
+
+diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
+index 55821343e5..289d00b01a 100644
+--- a/hw/9pfs/9p.c
++++ b/hw/9pfs/9p.c
+@@ -498,9 +498,9 @@ static int coroutine_fn v9fs_mark_fids_unreclaim(V9fsPDU *pdu, V9fsPath *path)
+ {
+     int err;
+     V9fsState *s = pdu->s;
+-    V9fsFidState *fidp, head_fid;
++    V9fsFidState *fidp;
+ 
+-    head_fid.next = s->fid_list;
++again:
+     for (fidp = s->fid_list; fidp; fidp = fidp->next) {
+         if (fidp->path.size != path->size) {
+             continue;
+@@ -520,7 +520,7 @@ static int coroutine_fn v9fs_mark_fids_unreclaim(V9fsPDU *pdu, V9fsPath *path)
+              * switched to the worker thread
+              */
+             if (err == 0) {
+-                fidp = &head_fid;
++                goto again;
+             }
+         }
+     }
+-- 
+2.27.0
+

qemu.spec

@@ -1,6 +1,6 @@
 Name: qemu
 Version: 4.1.0
-Release: 48
+Release: 49
 Epoch: 2
 Summary: QEMU is a generic and open source machine emulator and virtualizer
 License: GPLv2 and BSD and MIT and CC-BY-SA-4.0
@@ -310,6 +310,7 @@ Patch0297: spapr_pci-add-spapr-msi-read-method.patch
 Patch0298: tz-ppc-add-dummy-read-write-methods.patch
 Patch0299: imx7-ccm-add-digprog-mmio-write-method.patch
 Patch0300: bugfix-fix-Uninitialized-Free-Vulnerability.patch
+Patch0301: 9pfs-Fully-restart-unreclaim-loop-CVE-2021-20181.patch
 
 BuildRequires: flex
 BuildRequires: bison
@@ -697,6 +698,9 @@ getent passwd qemu >/dev/null || \
 %endif
 
 %changelog
+* Tue Jun 08 2021 Chen Qun <kuhn.chenqun@huawei.com>
+- 9pfs: Fully restart unreclaim loop (CVE-2021-20181)
+
 * Wed Jun 02 2021 imxcc <xingchaochao@huawei.com>
 - add strip for block-iscsi.so, block-rbd.so and block-ssh.so