[PATCH 2/9] EDAC/versalnet: Add NULL check for mci in remove_one_mc()

If a controller's configuration specifies an unrecognized bus width,
init_one_mc() returns 0 but skips allocating priv->mci[ctl_num], leaving
it NULL. On module unload or probe failure, remove_one_mc() is called for
all controllers and unconditionally dereferences priv->mci[i], causing a
kernel panic.

Add a NULL pointer check for mci before dereferencing it.

 Unable to handle kernel NULL pointer dereference at virtual address 0000000000000390
 Internal error: Oops: 0000000096000004 [#1] SMP
 Hardware name: Xilinx Versal NET VNX (DT)
 pc : mc_remove+0x34/0x88
 lr : mc_remove+0x4c/0x88
 Call trace:
  mc_remove+0x34/0x88
  platform_remove+0x2c/0x70
  device_remove+0x48/0x7c
  device_release_driver_internal+0x1c8/0x224
  device_driver_detach+0x18/0x28
  unbind_store+0xb4/0xb8

Fixes: 62a9fc50e8d9 ("EDAC/versalnet: Refactor memory controller initialization and cleanup")
Cc: [email protected]
Signed-off-by: Shubhrajyoti Datta <[email protected]>
---

 drivers/edac/versalnet_edac.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/edac/versalnet_edac.c b/drivers/edac/versalnet_edac.c
index 316f8f79c4d8..05dc34504cc2 100644
--- a/drivers/edac/versalnet_edac.c
+++ b/drivers/edac/versalnet_edac.c
@@ -769,6 +769,9 @@ static void remove_one_mc(struct mc_priv *priv, int i)
 	struct mem_ctl_info *mci;
 
 	mci = priv->mci[i];
+	if (!mci)
+		return;
+
 	device_unregister(mci->pdev);
 	edac_mc_del_mc(mci->pdev);
 	edac_mc_free(mci);
-- 
2.34.1