[tip: irq/urgent] genirq/msi: Take the per-device MSI lock before validating the control structure

[tip-bot2 for Marc Zyngier]

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

Commit-ID:     0af2795f936f1ea1f9f1497447145dfcc7ed2823
Gitweb:        https://git.kernel.org/tip/0af2795f936f1ea1f9f1497447145dfcc7ed2823
Author:        Marc Zyngier <maz@xxxxxxxxxx>
AuthorDate:    Mon, 20 Feb 2023 19:01:01 
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Mon, 20 Feb 2023 22:29:54 +01:00

genirq/msi: Take the per-device MSI lock before validating the control structure

Calling msi_ctrl_valid() ultimately results in calling
msi_get_device_domain(), which requires holding the device MSI lock.

However, in msi_domain_populate_irqs() the lock is taken right after having
called msi_ctrl_valid(), which is just a tad too late.

Take the lock before invoking msi_ctrl_valid().

Fixes: 40742716f294 ("genirq/msi: Make msi_add_simple_msi_descs() device domain aware")
Reported-by: "Russell King (Oracle)" <linux@xxxxxxxxxxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Tested-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/Y/Opu6ETe3ZzZ/8E@xxxxxxxxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20230220190101.314446-1-maz@xxxxxxxxxx

---
 kernel/irq/msi.c |  9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index 783a3e6..13d9649 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -1084,10 +1084,13 @@ int msi_domain_populate_irqs(struct irq_domain *domain, struct device *dev,
 	struct xarray *xa;
 	int ret, virq;
 
-	if (!msi_ctrl_valid(dev, &ctrl))
-		return -EINVAL;
-
 	msi_lock_descs(dev);
+
+	if (!msi_ctrl_valid(dev, &ctrl)) {
+		ret = -EINVAL;
+		goto unlock;
+	}
+
 	ret = msi_domain_add_simple_msi_descs(dev, &ctrl);
 	if (ret)
 		goto unlock;