linux-kernel - [PATCH] firmware: arm_scpi: Fix string overflow in SCPI genpd driver

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Date:   Mon,  6 Dec 2021 15:31:50 +0000
From:   Sudeep Holla <sudeep.holla@....com>
To:     linux-kernel@...r.kernel.org
Cc:     Sudeep Holla <sudeep.holla@....com>,
        Pedro Batista <pedbap.g@...il.com>,
        Cristian Marussi <cristian.marussi@....com>
Subject: [PATCH] firmware: arm_scpi: Fix string overflow in SCPI genpd driver

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 kasprintf and devm_kstrdup 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@...il.com>
Cc: Cristian Marussi <cristian.marussi@....com>
Signed-off-by: Sudeep Holla <sudeep.holla@....com>
---
 drivers/firmware/scpi_pm_domain.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/scpi_pm_domain.c b/drivers/firmware/scpi_pm_domain.c
index 51201600d789..377272c06ac3 100644
--- a/drivers/firmware/scpi_pm_domain.c
+++ b/drivers/firmware/scpi_pm_domain.c
@@ -11,12 +11,12 @@
 #include <linux/of_platform.h>
 #include <linux/pm_domain.h>
 #include <linux/scpi_protocol.h>
+#include <linux/slab.h>

 struct scpi_pm_domain {
 	struct generic_pm_domain genpd;
 	struct scpi_ops *ops;
 	u32 domain;
-	char name[30];
 };

 /*
@@ -106,12 +106,18 @@ static int scpi_pm_domain_probe(struct platform_device *pdev)
 		return -ENOMEM;

 	for (i = 0; i < num_domains; i++, scpi_pd++) {
+		const char *name = kasprintf(GFP_KERNEL, "%pOFn%d", np, i);
+
 		domains[i] = &scpi_pd->genpd;

 		scpi_pd->domain = i;
 		scpi_pd->ops = scpi_ops;
-		sprintf(scpi_pd->name, "%pOFn.%d", np, i);
-		scpi_pd->genpd.name = scpi_pd->name;
+		scpi_pd->genpd.name = devm_kstrdup(dev, name, GFP_KERNEL);
+		if (!scpi_pd->genpd.name) {
+			dev_err(dev, "Failed to allocate genpd name for %s\n",
+				name);
+			continue;
+		}
 		scpi_pd->genpd.power_off = scpi_pd_power_off;
 		scpi_pd->genpd.power_on = scpi_pd_power_on;

@@ -122,6 +128,7 @@ static int scpi_pm_domain_probe(struct platform_device *pdev)
 		 * but for reference counting purpose, keep it this way.
 		 */
 		pm_genpd_init(&scpi_pd->genpd, NULL, true);
+		kfree(name);
 	}

 	scpi_pd_data->domains = domains;
--
2.25.1