[PATCH 2/4] sparc: led: reject zero-length proc writes

[Pengpeng Hou]

led_proc_write() passes count straight through memdup_user_nul() and then
unconditionally inspects buf[count - 1] to strip a trailing newline. A
zero-length write therefore dereferences one byte before the allocated
buffer.

Reject empty writes before touching buf[count - 1].

Fixes: ee1858d3122d ("[SPARC]: Add sun4m LED driver.")
Signed-off-by: Pengpeng Hou <pengpeng@xxxxxxxxxxx>
---
 arch/sparc/kernel/led.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/sparc/kernel/led.c b/arch/sparc/kernel/led.c
index f4fb82b019bb..b9758fdbc054 100644
--- a/arch/sparc/kernel/led.c
+++ b/arch/sparc/kernel/led.c
@@ -70,6 +70,9 @@ static ssize_t led_proc_write(struct file *file, const char __user *buffer,
 {
 	char *buf = NULL;
 
+	if (!count)
+		return -EINVAL;
+
 	if (count > LED_MAX_LENGTH)
 		count = LED_MAX_LENGTH;
 
-- 
2.50.1 (Apple Git-155)