From 7eb475e8a738ee6fd1260aa59ddccb610fdd4300 Mon Sep 17 00:00:00 2001 From: Pengpeng Hou Date: Mon, 15 Jun 2026 13:58:50 +0800 Subject: [PATCH] sparc: led: avoid trimming a newline from empty writes led_proc_write() duplicates up to LED_MAX_LENGTH bytes with memdup_user_nul() and then unconditionally inspects buf[count - 1] to strip a trailing newline. A zero-length write therefore reads one byte before the duplicated buffer. The previous version rejected empty writes, but empty input already falls through to the existing default case and turns the LED off like any other unrecognized string. Preserve that behavior and only skip the newline trim when there is no input byte to inspect. Fixes: ee1858d3122d ("[SPARC]: Add sun4m LED driver.") Suggested-by: Andreas Larsson Signed-off-by: Pengpeng Hou Signed-off-by: Andreas Larsson --- arch/sparc/kernel/led.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/sparc/kernel/led.c b/arch/sparc/kernel/led.c index f4fb82b019bb9..9b53ac1fe533d 100644 --- a/arch/sparc/kernel/led.c +++ b/arch/sparc/kernel/led.c @@ -78,7 +78,7 @@ static ssize_t led_proc_write(struct file *file, const char __user *buffer, return PTR_ERR(buf); /* work around \n when echo'ing into proc */ - if (buf[count - 1] == '\n') + if (count > 0 && buf[count - 1] == '\n') buf[count - 1] = '\0'; /* before we change anything we want to stop any running timers, -- 2.47.3