[PATCH v2] usb: chipidea: otg: fix invalid role name print when no current role

[Xu Yang <xu.yang_2@oss.nxp.com>]

From: Xu Yang <xu.yang_2@nxp.com>

ci_handle_id_switch() prints the role transition via ci_role(ci)->name
for the current role, but when ci->role is CI_ROLE_END (no role
assigned yet), ci_role(ci) call BUG_ON() and return ci->roles[CI_ROLE_END]
which will cause invalid memory access in the debug print.

This can happen if ci_role_start() fails during a role switch, since
ci_role_stop() has already set ci->role to CI_ROLE_END.

Fix it by printing "none" instead of dereferencing ci_role(ci)->name
when ci->role is not a valid role.

Fixes: cbec6bd55a45 ("usb: chipidea: move otg related things to otg file")
Cc: stable@vger.kernel.org
Signed-off-by: Xu Yang <xu.yang_2@nxp.com>

---
Changes in v2:
 - improve commit message
 - use " >= " sign
---
 drivers/usb/chipidea/otg.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/chipidea/otg.c b/drivers/usb/chipidea/otg.c
index fecc7d7e2f0d..5eb3b32c2e87 100644
--- a/drivers/usb/chipidea/otg.c
+++ b/drivers/usb/chipidea/otg.c
@@ -179,7 +179,8 @@ void ci_handle_id_switch(struct ci_hdrc *ci)
 	role = ci_otg_role(ci);
 	if (role != ci->role) {
 		dev_dbg(ci->dev, "switching from %s to %s\n",
-			ci_role(ci)->name, ci->roles[role]->name);
+			ci->role >= CI_ROLE_END ? "none" : ci_role(ci)->name,
+			ci->roles[role]->name);
 
 		if (ci->vbus_active && ci->role == CI_ROLE_GADGET)
 			/*
-- 
2.34.1