[PATCH] usb: typec: ucsi: Fix null pointer dereference in ucsi_sync_control_common

["Mario Limonciello (AMD)" <superm1@kernel.org>]

Add missing null check for cci parameter before dereferencing it in
ucsi_sync_control_common(). The function can be called with cci=NULL
from ucsi_acknowledge(), which leads to a null pointer dereference
when accessing *cci in the condition check.

The crash occurs because the code checks if cci is not null before
calling ucsi->ops->read_cci(ucsi, cci), but then immediately
dereferences cci without a null check in the following condition:
(*cci & UCSI_CCI_COMMAND_COMPLETE).

KASAN trace:
  KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
  RIP: 0010:ucsi_sync_control_common+0x2ae/0x4e0 [typec_ucsi]

Fixes: 667ecac55861 ("usb: typec: ucsi: return CCI and message from sync_control callback")
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
---
 drivers/usb/typec/ucsi/ucsi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
index 9b3df776137a1..7129973f19e7e 100644
--- a/drivers/usb/typec/ucsi/ucsi.c
+++ b/drivers/usb/typec/ucsi/ucsi.c
@@ -97,7 +97,7 @@ int ucsi_sync_control_common(struct ucsi *ucsi, u64 command, u32 *cci)
 	if (!ret && cci)
 		ret = ucsi->ops->read_cci(ucsi, cci);
 
-	if (!ret && ucsi->message_in_size > 0 &&
+	if (!ret && cci && ucsi->message_in_size > 0 &&
 	    (*cci & UCSI_CCI_COMMAND_COMPLETE))
 		ret = ucsi->ops->read_message_in(ucsi, ucsi->message_in,
 						 ucsi->message_in_size);
-- 
2.43.0