diff options
| author | Wang Hai <wanghai38@huawei.com> | 2020-06-12 12:08:33 +0300 |
|---|---|---|
| committer | Dominique Martinet <asmadeus@codewreck.org> | 2020-07-19 15:58:47 +0300 |
| commit | 74d6a5d5662975aed7f25952f62efbb6f6dadd29 (patch) | |
| tree | c31cb1d3bcd23daf8d7e73df4616025b6be93ace | |
| parent | a39c46067c845a8a2d7144836e9468b7f072343e (diff) | |
| download | linux-74d6a5d5662975aed7f25952f62efbb6f6dadd29.tar.xz | |
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>
| -rw-r--r-- | net/9p/trans_fd.c | 15 |
1 files changed, 14 insertions, 1 deletions
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); |