9p/trans_fd: abort p9_read_work if req status changed (e4ca13f7) · Commits · 戴 / test

p9_read_work would try to handle an errored req even if it got put to error state by another thread between the lookup (that worked) and the time it had been fully read. The request itself is safe to use because we hold a ref to it from the lookup (for m->rreq, so it was safe to read into the request data buffer until this point), but the req_list has been deleted at the same time status changed, and client_cb already has been called as well, so we should not do either. Link: http://lkml.kernel.org/r/1539057956-23741-1-git-send-email-asmadeus@codewreck.org Signed-off-by:

Dominique Martinet <dominique.martinet@cea.fr> Reported-by:

<syzbot+2222c34dc40b515f30dc@syzkaller.appspotmail.com> Cc: Eric Van Hensbergen <ericvh@gmail.com> Cc: Latchesar Ionkov <lucho@ionkov.net>

net/9p/trans_fd.c

+11 −6

Original line number	Diff line number	Diff line
		@@ -292,7 +292,6 @@ static void p9_read_work(struct work_struct *work)
		__poll_t n;
		int err;
		struct p9_conn *m;
		int status = REQ_STATUS_ERROR;

		m = container_of(work, struct p9_conn, rq);

		@@ -375,11 +374,17 @@ static void p9_read_work(struct work_struct *work)
		p9_debug(P9_DEBUG_TRANS, "got new packet\n");
		m->rreq->rc.size = m->rc.offset;
		spin_lock(&m->client->lock);
		if (m->rreq->status != REQ_STATUS_ERROR)
		status = REQ_STATUS_RCVD;
		if (m->rreq->status == REQ_STATUS_SENT) {
		list_del(&m->rreq->req_list);
		/* update req->status while holding client->lock */
		p9_client_cb(m->client, m->rreq, status);
		p9_client_cb(m->client, m->rreq, REQ_STATUS_RCVD);
		} else {
		spin_unlock(&m->client->lock);
		p9_debug(P9_DEBUG_ERROR,
		"Request tag %d errored out while we were reading the reply\n",
		m->rc.tag);
		err = -EIO;
		goto error;
		}
		spin_unlock(&m->client->lock);
		m->rc.sdata = NULL;
		m->rc.offset = 0;

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