[PATCH] [BACKPORT v4.9 - v4.19] firmware: arm_scpi: Fix string overflow in SCPI genpd driver

[Sudeep Holla]

commit 865ed67ab955428b9aa771d8b4f1e4fb7fd08945 upstream.

Without the bound checks for scpi_pd->name, it could result in the buffer
overflow when copying the SCPI device name from the corresponding device
tree node as the name string is set at maximum size of 30.

Let us fix it by using devm_kasprintf so that the string buffer is
allocated dynamically.

Fixes: 8bec4337ad40 ("firmware: scpi: add device power domain support using genpd")
Reported-by: Pedro Batista <pedbap.g@xxxxxxxxx>
Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx #v4.9, v4.14, v4.19
Cc: Cristian Marussi <cristian.marussi@xxxxxxx>
Link: https://lore.kernel.org/r/20211209120456.696879-1-sudeep.holla@xxxxxxx
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
 drivers/firmware/scpi_pm_domain.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/scpi_pm_domain.c b/drivers/firmware/scpi_pm_domain.c
index f395dec27113..a6e62a793fbe 100644
--- a/drivers/firmware/scpi_pm_domain.c
+++ b/drivers/firmware/scpi_pm_domain.c
@@ -27,7 +27,6 @@ struct scpi_pm_domain {
 	struct generic_pm_domain genpd;
 	struct scpi_ops *ops;
 	u32 domain;
-	char name[30];
 };
 
 /*
@@ -121,8 +120,13 @@ static int scpi_pm_domain_probe(struct platform_device *pdev)
 
 		scpi_pd->domain = i;
 		scpi_pd->ops = scpi_ops;
-		sprintf(scpi_pd->name, "%s.%d", np->name, i);
-		scpi_pd->genpd.name = scpi_pd->name;
+		scpi_pd->genpd.name = devm_kasprintf(dev, GFP_KERNEL,
+						     "%s.%d", np->name, i);
+		if (!scpi_pd->genpd.name) {
+			dev_err(dev, "Failed to allocate genpd name:%s.%d\n",
+				np->name, i);
+			continue;
+		}
 		scpi_pd->genpd.power_off = scpi_pd_power_off;
 		scpi_pd->genpd.power_on = scpi_pd_power_on;
 
-- 
2.25.1