[tip: irq/urgent] irqchip/irq-msi-lib: Check for NULL ops in msi_lib_irq_domain_select()

[tip-bot2 for Maxime Chevallier]

The following commit has been merged into the irq/urgent branch of tip:

Commit-ID:     880799fc7a3a127c43143935c1a8767d77c19cae
Gitweb:        https://git.kernel.org/tip/880799fc7a3a127c43143935c1a8767d77c19cae
Author:        Maxime Chevallier <maxime.chevallier@xxxxxxxxxxx>
AuthorDate:    Fri, 23 Aug 2024 12:07:12 +02:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Fri, 23 Aug 2024 13:55:15 +02:00

irqchip/irq-msi-lib: Check for NULL ops in msi_lib_irq_domain_select()

The irq_domain passed to msi_lib_irq_domain_select() may not have
msi_parent_ops set. There is a NULL pointer check for it, but unfortunately
there is a dereference of the parent ops pointer before that.

Move the NULL pointer test before the first use of that pointer.

This was found on a MacchiatoBin (Marvell Armada 8K SoC), which uses the
irq-mvebu-sei driver.

Fixes: 72e257c6f058 ("irqchip: Provide irq-msi-lib")
Signed-off-by: Maxime Chevallier <maxime.chevallier@xxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/all/20240823100733.1900666-1-maxime.chevallier@xxxxxxxxxxx
Closes: https://lore.kernel.org/all/20240821165034.1af97bad@xxxxxxxxxxxxx/
---
 drivers/irqchip/irq-msi-lib.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-msi-lib.c b/drivers/irqchip/irq-msi-lib.c
index b5b9000..d8e29fc 100644
--- a/drivers/irqchip/irq-msi-lib.c
+++ b/drivers/irqchip/irq-msi-lib.c
@@ -128,6 +128,9 @@ int msi_lib_irq_domain_select(struct irq_domain *d, struct irq_fwspec *fwspec,
 	const struct msi_parent_ops *ops = d->msi_parent_ops;
 	u32 busmask = BIT(bus_token);
 
+	if (!ops)
+		return 0;
+
 	if (fwspec->fwnode != d->fwnode || fwspec->param_count != 0)
 		return 0;
 
@@ -135,6 +138,6 @@ int msi_lib_irq_domain_select(struct irq_domain *d, struct irq_fwspec *fwspec,
 	if (bus_token == ops->bus_select_token)
 		return 1;
 
-	return ops && !!(ops->bus_select_mask & busmask);
+	return !!(ops->bus_select_mask & busmask);
 }
 EXPORT_SYMBOL_GPL(msi_lib_irq_domain_select);