linux-kernel - [PATCH 3/3] i3c: master: Fix dynamic address leak when 'assigned-address' is present

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Message-Id: <20241001-i3c_dts_assign-v1-3-6ba83dc15eb8@nxp.com>
Date: Tue, 01 Oct 2024 13:08:22 -0400
From: Frank Li <Frank.Li@....com>
To: Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc: linux-i3c@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 arnd@...db.de, bbrezillon@...nel.org, boris.brezillon@...labora.com, 
 conor.culhane@...vaco.com, gregkh@...uxfoundation.org, imx@...ts.linux.dev, 
 miquel.raynal@...tlin.com, pthombar@...ence.com, 
 ravindra.yashvant.shinde@....com, Frank Li <Frank.Li@....com>, 
 stable@...nel.org
Subject: [PATCH 3/3] i3c: master: Fix dynamic address leak when
 'assigned-address' is present

If the DTS contains 'assigned-address', a dynamic address leak occurs
during hotjoin events.

Assume a device have assigned-address 0xb.
  - Device issue Hotjoin
  - Call i3c_master_do_daa()
  - Call driver xxx_do_daa()
  - Call i3c_master_get_free_addr() to get dynamic address 0x9
  - i3c_master_add_i3c_dev_locked(0x9)
  -     expected_dyn_addr  = newdev->boardinfo->init_dyn_addr (0xb);
  -     i3c_master_reattach_i3c_dev(newdev(0xb), old_dyn_addr(0x9));
  -         if (dev->info.dyn_addr != old_dyn_addr &&
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 0xb != 0x9 -> TRUE
                (!dev->boardinfo ||
                 ^^^^^^^^^^^^^^^ ->  FALSE
                 dev->info.dyn_addr != dev->boardinfo->init_dyn_addr)) {
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                 0xb != 0xb      ->  FALSE
                 ...
                 i3c_bus_set_addr_slot_status(&master->bus, old_dyn_addr,
                                                     I3C_ADDR_SLOT_FREE);
		 ^^^
                 This will be skipped. So old_dyn_addr never free
            }

  - i3c_master_get_free_addr() will return increased sequence number.

Remove dev->info.dyn_addr != dev->boardinfo->init_dyn_addr condition check.
dev->info.dyn_addr should be checked before calling this function because
i3c_master_setnewda_locked() has already been called and the target device
has already accepted dyn_addr. It is too late to check if dyn_addr is free
in i3c_master_reattach_i3c_dev().

Add check to ensure expected_dyn_addr is free before
i3c_master_setnewda_locked().

Fixes: cc3a392d69b6 ("i3c: master: fix for SETDASA and DAA process")
Cc: stable@...nel.org
Signed-off-by: Frank Li <Frank.Li@....com>
---
Change v3 to v4
- none
---
 drivers/i3c/master.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index a56cb281e6b6d..eae7449f0dacb 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -1556,16 +1556,9 @@ static int i3c_master_reattach_i3c_dev(struct i3c_dev_desc *dev,
 				       u8 old_dyn_addr)
 {
 	struct i3c_master_controller *master = i3c_dev_get_master(dev);
-	enum i3c_addr_slot_status status;
 	int ret;
 
-	if (dev->info.dyn_addr != old_dyn_addr &&
-	    (!dev->boardinfo ||
-	     dev->info.dyn_addr != dev->boardinfo->init_dyn_addr)) {
-		status = i3c_bus_get_addr_slot_status(&master->bus,
-						      dev->info.dyn_addr);
-		if (status != I3C_ADDR_SLOT_FREE)
-			return -EBUSY;
+	if (dev->info.dyn_addr != old_dyn_addr) {
 		i3c_bus_set_addr_slot_status(&master->bus,
 					     dev->info.dyn_addr,
 					     I3C_ADDR_SLOT_I3C_DEV);
@@ -1968,9 +1961,10 @@ static int i3c_master_bus_init(struct i3c_master_controller *master)
 			goto err_rstdaa;
 		}
 
+		/* Not mark as occupied until real device exist in bus */
 		i3c_bus_set_addr_slot_status_ext(&master->bus,
 						 i3cboardinfo->init_dyn_addr,
-						 I3C_ADDR_SLOT_I3C_DEV | I3C_ADDR_SLOT_EXT_INIT);
+						 I3C_ADDR_SLOT_EXT_INIT);
 
 		/*
 		 * Only try to create/attach devices that have a static
@@ -2133,7 +2127,8 @@ int i3c_master_add_i3c_dev_locked(struct i3c_master_controller *master,
 	else
 		expected_dyn_addr = newdev->info.dyn_addr;
 
-	if (newdev->info.dyn_addr != expected_dyn_addr) {
+	if (newdev->info.dyn_addr != expected_dyn_addr &&
+	    i3c_bus_get_addr_slot_status(&master->bus, expected_dyn_addr) == I3C_ADDR_SLOT_FREE) {
 		/*
 		 * Try to apply the expected dynamic address. If it fails, keep
 		 * the address assigned by the master.

-- 
2.34.1