i3c: master: svc: fix possible assignment of the same address to two …

…devices

commit 3b2ac81 upstream.

svc_i3c_master_do_daa() {
    ...
    for (i = 0; i < dev_nb; i++) {
        ret = i3c_master_add_i3c_dev_locked(m, addrs[i]);
        if (ret)
            goto rpm_out;
    }
}

If two devices (A and B) are detected in DAA and address 0xa is assigned to
device A and 0xb to device B, a failure in i3c_master_add_i3c_dev_locked()
for device A (addr: 0xa) could prevent device B (addr: 0xb) from being
registered on the bus. The I3C stack might still consider 0xb a free
address. If a subsequent Hotjoin occurs, 0xb might be assigned to Device A,
causing both devices A and B to use the same address 0xb, violating the I3C
specification.

The return value for i3c_master_add_i3c_dev_locked() should not be checked
because subsequent steps will scan the entire I3C bus, independent of
whether i3c_master_add_i3c_dev_locked() returns success.

If device A registration fails, there is still a chance to register device
B. i3c_master_add_i3c_dev_locked() can reset DAA if a failure occurs while
retrieving device information.

Cc: [email protected]
Fixes: 317bacf ("i3c: master: add enable(disable) hot join in sys entry")
Reviewed-by: Miquel Raynal <[email protected]>
Signed-off-by: Frank Li <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexandre Belloni <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

drivers/i3c/master/svc-i3c-master.c

@@ -1018,12 +1018,27 @@ static int svc_i3c_master_do_daa(struct i3c_master_controller *m)
 		goto rpm_out;
 	}
 
-	/* Register all devices who participated to the core */
-	for (i = 0; i < dev_nb; i++) {
-		ret = i3c_master_add_i3c_dev_locked(m, addrs[i]);
-		if (ret)
-			goto rpm_out;
-	}
+	/*
+	 * Register all devices who participated to the core
+	 *
+	 * If two devices (A and B) are detected in DAA and address 0xa is assigned to
+	 * device A and 0xb to device B, a failure in i3c_master_add_i3c_dev_locked()
+	 * for device A (addr: 0xa) could prevent device B (addr: 0xb) from being
+	 * registered on the bus. The I3C stack might still consider 0xb a free
+	 * address. If a subsequent Hotjoin occurs, 0xb might be assigned to Device A,
+	 * causing both devices A and B to use the same address 0xb, violating the I3C
+	 * specification.
+	 *
+	 * The return value for i3c_master_add_i3c_dev_locked() should not be checked
+	 * because subsequent steps will scan the entire I3C bus, independent of
+	 * whether i3c_master_add_i3c_dev_locked() returns success.
+	 *
+	 * If device A registration fails, there is still a chance to register device
+	 * B. i3c_master_add_i3c_dev_locked() can reset DAA if a failure occurs while
+	 * retrieving device information.
+	 */
+	for (i = 0; i < dev_nb; i++)
+		i3c_master_add_i3c_dev_locked(m, addrs[i]);
 
 	/* Configure IBI auto-rules */
 	ret = svc_i3c_update_ibirules(master);