[PATCH] riscv: cpuinfo: Fix NULL dereference and inconsistent error code

From: Mohamed Ayman <mohamedaymanworkspace@gmail.com>
To: Paul Walmsley <pjw@kernel.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Alexandre Ghiti <alex@ghiti.fr>,
	Andrew Jones <ajones@ventanamicro.com>,
	Conor Dooley <conor.dooley@microchip.com>,
	Anup Patel <apatel@ventanamicro.com>,
	Mohamed Ayman <mohamedaymanworkspace@gmail.com>,
	linux-riscv@lists.infradead.org (open list:RISC-V ARCHITECTURE),
	linux-kernel@vger.kernel.org (open list)
Cc: linux-riscv@lists.infradead.org (open list:RISC-V ARCHITECTURE),
	linux-kernel@vger.kernel.org (open list)
Subject: [PATCH] riscv: cpuinfo: Fix NULL dereference and inconsistent error code
Date: Sat,  2 May 2026 19:02:57 +0300	[thread overview]
Message-ID: <20260502160301.453029-1-mohamedaymanworkspace@gmail.com> (raw)

Fix a potential NULL pointer dereference in c_show() by ensuring
the device tree node returned by of_get_cpu_node() is checked before use.

Also replace a non-standard return value (-1) in
riscv_of_parent_hartid() with -ENODEV to follow Linux kernel
conventions for "not found" error returns.

Both issues improve robustness and consistency with existing RISC-V CPU info handling code.
---
 arch/riscv/kernel/cpu.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index 3dbc8cc557dd..e0bc7526861f 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -135,7 +135,7 @@ int riscv_of_parent_hartid(struct device_node *node, unsigned long *hartid)
 		}
 	}
 
-	return -1;
+	return -ENODEV;
 }
 
 unsigned long __init riscv_get_marchid(void)
@@ -348,12 +348,13 @@ static int c_show(struct seq_file *m, void *v)
 
 	if (acpi_disabled) {
 		node = of_get_cpu_node(cpu_id, NULL);
+		if (node) {
+			if (!of_property_read_string(node, "compatible", &compat) &&
+				strcmp(compat, "riscv"))
+				seq_printf(m, "uarch\t\t: %s\n", compat);
 
-		if (!of_property_read_string(node, "compatible", &compat) &&
-		    strcmp(compat, "riscv"))
-			seq_printf(m, "uarch\t\t: %s\n", compat);
-
-		of_node_put(node);
+			of_node_put(node);
+		}
 	}
 
 	seq_printf(m, "mvendorid\t: 0x%lx\n", ci->mvendorid);
-- 
2.34.1


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