[PATCH] drivers/char/ipmi_si: prevent null deref during module exit

[Andrew Banman]

If there are uninitialized SMIs in the smi_infos list, i.e. with no
handlers set, then disable_si_irq() in cleanup_smi_one() will hit a null
pointer dereference when the former attempts to start the check enables
transaction. Thus, we panic during module exit.

Avoid panicking when there are uninitialized SMIs by checking for a handler
pointer before starting the check enables transaction.

Signed-off-by: Andrew Banman <abanman@xxxxxxx>
---
 drivers/char/ipmi/ipmi_si_intf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
index cb5719e..6c0b1b3 100644
--- a/drivers/char/ipmi/ipmi_si_intf.c
+++ b/drivers/char/ipmi/ipmi_si_intf.c
@@ -442,7 +442,7 @@ static void start_check_enables(struct smi_info *smi_info, 
bool start_timer)

 	if (start_timer)
 		start_new_msg(smi_info, msg, 2);
-	else
+	else if (smi_info->handlers)
 		smi_info->handlers->start_transaction(smi_info->si_sm, msg, 2);
 	smi_info->si_state = SI_CHECKING_ENABLES;
 }
--
1.8.2.1