i3c: master: mipi-i3c-hci: Fix a kernel panic for accessing DAT_data.

The `i3c_master_bus_init` function may attach the I2C devices before the
I3C bus initialization. In this flow, the DAT `alloc_entry`` will be used
before the DAT `init`. Additionally, if the `i3c_master_bus_init` fails,
the DAT `cleanup` will execute before the device is detached, which will
execue DAT `free_entry` function. The above scenario can cause the driver
to use DAT_data when it is NULL.

Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com>
Link: https://lore.kernel.org/r/20231023080237.560936-1-billy_tsai@aspeedtech.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/drivers/i3c/master/mipi-i3c-hci/dat_v1.c b/drivers/i3c/master/mipi-i3c-hci/dat_v1.c
index 97bb49ff5b53bd8887303471a8b6446470156a81..47b9b4d4ed3fc0ff5e05ed4d4d2d5b28ae246ded 100644 (file)
--- a/drivers/i3c/master/mipi-i3c-hci/dat_v1.c
+++ b/drivers/i3c/master/mipi-i3c-hci/dat_v1.c
@@ -64,15 +64,17 @@ static int hci_dat_v1_init(struct i3c_hci *hci)
                return -EOPNOTSUPP;
        }
 
-       /* use a bitmap for faster free slot search */
-       hci->DAT_data = bitmap_zalloc(hci->DAT_entries, GFP_KERNEL);
-       if (!hci->DAT_data)
-               return -ENOMEM;
-
-       /* clear them */
-       for (dat_idx = 0; dat_idx < hci->DAT_entries; dat_idx++) {
-               dat_w0_write(dat_idx, 0);
-               dat_w1_write(dat_idx, 0);
+       if (!hci->DAT_data) {
+               /* use a bitmap for faster free slot search */
+               hci->DAT_data = bitmap_zalloc(hci->DAT_entries, GFP_KERNEL);
+               if (!hci->DAT_data)
+                       return -ENOMEM;
+
+               /* clear them */
+               for (dat_idx = 0; dat_idx < hci->DAT_entries; dat_idx++) {
+                       dat_w0_write(dat_idx, 0);
+                       dat_w1_write(dat_idx, 0);
+               }
        }
 
        return 0;
@@ -87,7 +89,13 @@ static void hci_dat_v1_cleanup(struct i3c_hci *hci)
 static int hci_dat_v1_alloc_entry(struct i3c_hci *hci)
 {
        unsigned int dat_idx;
+       int ret;
 
+       if (!hci->DAT_data) {
+               ret = hci_dat_v1_init(hci);
+               if (ret)
+                       return ret;
+       }
        dat_idx = find_first_zero_bit(hci->DAT_data, hci->DAT_entries);
        if (dat_idx >= hci->DAT_entries)
                return -ENOENT;
@@ -103,7 +111,8 @@ static void hci_dat_v1_free_entry(struct i3c_hci *hci, unsigned int dat_idx)
 {
        dat_w0_write(dat_idx, 0);
        dat_w1_write(dat_idx, 0);
-       __clear_bit(dat_idx, hci->DAT_data);
+       if (hci->DAT_data)
+               __clear_bit(dat_idx, hci->DAT_data);
 }
 
 static void hci_dat_v1_set_dynamic_addr(struct i3c_hci *hci,