From: <gregkh@linuxfoundation.org>
To: wanghai38@huawei.com, asmadeus@codewreck.org, stable@vger.kernel.org
Cc: <stable@vger.kernel.org>
Subject: FAILED: patch "[PATCH] 9p/trans_fd: Fix concurrency del of req_list in" failed to apply to 4.9-stable tree
Date: Sat, 01 Aug 2020 13:46:34 +0200 [thread overview]
Message-ID: <1596282394253233@kroah.com> (raw)
The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 74d6a5d5662975aed7f25952f62efbb6f6dadd29 Mon Sep 17 00:00:00 2001
From: Wang Hai <wanghai38@huawei.com>
Date: Fri, 12 Jun 2020 17:08:33 +0800
Subject: [PATCH] 9p/trans_fd: Fix concurrency del of req_list in
p9_fd_cancelled/p9_read_work
p9_read_work and p9_fd_cancelled may be called concurrently.
In some cases, req->req_list may be deleted by both p9_read_work
and p9_fd_cancelled.
We can fix it by ignoring replies associated with a cancelled
request and ignoring cancelled request if message has been received
before lock.
Link: http://lkml.kernel.org/r/20200612090833.36149-1-wanghai38@huawei.com
Fixes: 60ff779c4abb ("9p: client: remove unused code and any reference to "cancelled" function")
Cc: <stable@vger.kernel.org> # v3.12+
Reported-by: syzbot+77a25acfa0382e06ab23@syzkaller.appspotmail.com
Signed-off-by: Wang Hai <wanghai38@huawei.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
index 9c9196d30a59..12ecacf0c55f 100644
--- a/net/9p/trans_fd.c
+++ b/net/9p/trans_fd.c
@@ -362,6 +362,10 @@ static void p9_read_work(struct work_struct *work)
if (m->rreq->status == REQ_STATUS_SENT) {
list_del(&m->rreq->req_list);
p9_client_cb(m->client, m->rreq, REQ_STATUS_RCVD);
+ } else if (m->rreq->status == REQ_STATUS_FLSHD) {
+ /* Ignore replies associated with a cancelled request. */
+ p9_debug(P9_DEBUG_TRANS,
+ "Ignore replies associated with a cancelled request\n");
} else {
spin_unlock(&m->client->lock);
p9_debug(P9_DEBUG_ERROR,
@@ -703,11 +707,20 @@ static int p9_fd_cancelled(struct p9_client *client, struct p9_req_t *req)
{
p9_debug(P9_DEBUG_TRANS, "client %p req %p\n", client, req);
+ spin_lock(&client->lock);
+ /* Ignore cancelled request if message has been received
+ * before lock.
+ */
+ if (req->status == REQ_STATUS_RCVD) {
+ spin_unlock(&client->lock);
+ return 0;
+ }
+
/* we haven't received a response for oldreq,
* remove it from the list.
*/
- spin_lock(&client->lock);
list_del(&req->req_list);
+ req->status = REQ_STATUS_FLSHD;
spin_unlock(&client->lock);
p9_req_put(req);
reply other threads:[~2020-08-01 11:47 UTC|newest]
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