Merge tag '9p-for-6.2-rc1' of https://github.com/martinetd/linux

Pull 9p updates from Dominique Martinet:

 - improve p9_check_errors to check buffer size instead of msize when
   possible (e.g. not zero-copy)

 - some more syzbot and KCSAN fixes

 - minor headers include cleanup

* tag '9p-for-6.2-rc1' of https://github.com/martinetd/linux:
  9p/client: fix data race on req->status
  net/9p: fix response size check in p9_check_errors()
  net/9p: distinguish zero-copy requests
  9p/xen: do not memcpy header into req->rc
  9p: set req refcount to zero to avoid uninitialized usage
  9p/net: Remove unneeded idr.h #include
  9p/fs: Remove unneeded idr.h #include

1 files changed, 22 insertions, 11 deletions

diff --git a/net/9p/client.c b/net/9p/client.c
index 0638b12055ba..622ec6a586ee 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -297,6 +297,11 @@ p9_tag_alloc(struct p9_client *c, int8_t type, uint t_size, uint r_size,
 	p9pdu_reset(&req->rc);
 	req->t_err = 0;
 	req->status = REQ_STATUS_ALLOC;
+	/* refcount needs to be set to 0 before inserting into the idr
+	 * so p9_tag_lookup does not accept a request that is not fully
+	 * initialized. refcount_set to 2 below will mark request ready.
+	 */
+	refcount_set(&req->refcount, 0);
 	init_waitqueue_head(&req->wq);
 	INIT_LIST_HEAD(&req->req_list);
 
@@ -438,7 +443,7 @@ void p9_client_cb(struct p9_client *c, struct p9_req_t *req, int status)
 	 * the status change is visible to another thread
 	 */
 	smp_wmb();
-	req->status = status;
+	WRITE_ONCE(req->status, status);
 
 	wake_up(&req->wq);
 	p9_debug(P9_DEBUG_MUX, "wakeup: %d\n", req->tc.tag);
@@ -514,10 +519,9 @@ static int p9_check_errors(struct p9_client *c, struct p9_req_t *req)
 	int ecode;
 
 	err = p9_parse_header(&req->rc, NULL, &type, NULL, 0);
-	if (req->rc.size >= c->msize) {
-		p9_debug(P9_DEBUG_ERROR,
-			 "requested packet size too big: %d\n",
-			 req->rc.size);
+	if (req->rc.size > req->rc.capacity && !req->rc.zc) {
+		pr_err("requested packet size too big: %d does not fit %zu (type=%d)\n",
+		       req->rc.size, req->rc.capacity, req->rc.id);
 		return -EIO;
 	}
 	/* dump the response from server
@@ -600,7 +604,7 @@ static int p9_client_flush(struct p9_client *c, struct p9_req_t *oldreq)
 	/* if we haven't received a response for oldreq,
 	 * remove it from the list
 	 */
-	if (oldreq->status == REQ_STATUS_SENT) {
+	if (READ_ONCE(oldreq->status) == REQ_STATUS_SENT) {
 		if (c->trans_mod->cancelled)
 			c->trans_mod->cancelled(c, oldreq);
 	}
@@ -680,6 +684,9 @@ p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...)
 	if (IS_ERR(req))
 		return req;
 
+	req->tc.zc = false;
+	req->rc.zc = false;
+
 	if (signal_pending(current)) {
 		sigpending = 1;
 		clear_thread_flag(TIF_SIGPENDING);
@@ -697,7 +704,8 @@ p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...)
 	}
 again:
 	/* Wait for the response */
-	err = wait_event_killable(req->wq, req->status >= REQ_STATUS_RCVD);
+	err = wait_event_killable(req->wq,
+				  READ_ONCE(req->status) >= REQ_STATUS_RCVD);
 
 	/* Make sure our req is coherent with regard to updates in other
 	 * threads - echoes to wmb() in the callback
@@ -711,7 +719,7 @@ again:
 		goto again;
 	}
 
-	if (req->status == REQ_STATUS_ERROR) {
+	if (READ_ONCE(req->status) == REQ_STATUS_ERROR) {
 		p9_debug(P9_DEBUG_ERROR, "req_status error %d\n", req->t_err);
 		err = req->t_err;
 	}
@@ -724,7 +732,7 @@ again:
 			p9_client_flush(c, req);
 
 		/* if we received the response anyway, don't signal error */
-		if (req->status == REQ_STATUS_RCVD)
+		if (READ_ONCE(req->status) == REQ_STATUS_RCVD)
 			err = 0;
 	}
 recalc_sigpending:
@@ -778,6 +786,9 @@ static struct p9_req_t *p9_client_zc_rpc(struct p9_client *c, int8_t type,
 	if (IS_ERR(req))
 		return req;
 
+	req->tc.zc = true;
+	req->rc.zc = true;
+
 	if (signal_pending(current)) {
 		sigpending = 1;
 		clear_thread_flag(TIF_SIGPENDING);
@@ -793,7 +804,7 @@ static struct p9_req_t *p9_client_zc_rpc(struct p9_client *c, int8_t type,
 		if (err != -ERESTARTSYS)
 			goto recalc_sigpending;
 	}
-	if (req->status == REQ_STATUS_ERROR) {
+	if (READ_ONCE(req->status) == REQ_STATUS_ERROR) {
 		p9_debug(P9_DEBUG_ERROR, "req_status error %d\n", req->t_err);
 		err = req->t_err;
 	}
@@ -806,7 +817,7 @@ static struct p9_req_t *p9_client_zc_rpc(struct p9_client *c, int8_t type,
 			p9_client_flush(c, req);
 
 		/* if we received the response anyway, don't signal error */
-		if (req->status == REQ_STATUS_RCVD)
+		if (READ_ONCE(req->status) == REQ_STATUS_RCVD)
 			err = 0;
 	}
 recalc_sigpending: