[irqchip: irq/irqchip-next] driver core: platform: Add extra error check in devm_platform_get_irqs_affinity()

[irqchip-bot for John Garry]

The following commit has been merged into the irq/irqchip-next branch of irqchip:

Commit-ID:     e1dc20995cb9fa04b46e8f37113a7203c906d2bf
Gitweb:        https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms/e1dc20995cb9fa04b46e8f37113a7203c906d2bf
Author:        John Garry <john.garry@xxxxxxxxxx>
AuthorDate:    Mon, 21 Dec 2020 22:30:55 +08:00
Committer:     Marc Zyngier <maz@xxxxxxxxxx>
CommitterDate: Tue, 22 Dec 2020 08:06:38 

driver core: platform: Add extra error check in devm_platform_get_irqs_affinity()

The current check of nvec < minvec for nvec returned from
platform_irq_count() will not detect a negative error code in nvec.

This is because minvec is unsigned, and, as such, nvec is promoted to
unsigned in that check, which will make it a huge number (if it contained
-EPROBE_DEFER).

In practice, an error should not occur in nvec for the only in-tree
user, but add a check anyway.

Fixes: e15f2fa959f2 ("driver core: platform: Add devm_platform_get_irqs_affinity()")
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Link: https://lore.kernel.org/r/1608561055-231244-1-git-send-email-john.garry@xxxxxxxxxx
---
 drivers/base/platform.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index ea8add1..74c97b6 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -351,6 +351,8 @@ int devm_platform_get_irqs_affinity(struct platform_device *dev,
 		return -ERANGE;
 
 	nvec = platform_irq_count(dev);
+	if (nvec < 0)
+		return nvec;
 
 	if (nvec < minvec)
 		return -ENOSPC;