linux-kernel - [PATCH v2] kconfig: nconf: Fix uncleared lines on help screens

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Message-Id: <20250722172837.140328-1-shankari.ak0208@gmail.com>
Date: Tue, 22 Jul 2025 22:58:37 +0530
From: Shankari Anand <shankari.ak0208@...il.com>
To: linux-kernel@...r.kernel.org,
	linux-kbuild@...r.kernel.org
Cc: Masahiro Yamada <masahiroy@...nel.org>,
	Shankari Anand <shankari.ak0208@...il.com>,
	Randy Dunlap <rdunlap@...radead.org>
Subject: [PATCH v2] kconfig: nconf: Fix uncleared lines on help screens

Commit 1b92b18ec419 ("kconfig: nconf: Ensure null termination where
strncpy is used") introduced a regression where
help screens (F1, F2, F3) no longer properly clear short lines of text,
resulting in duplicated or trailing content when lines are overwritten.

Revert the null-termination change to match
the actual length of the copied string.

Reported-by: Randy Dunlap <rdunlap@...radead.org>
Closes: https://lore.kernel.org/lkml/CAK7LNAT54nvwYmTy20Ep8U2kr4thn68yYWXi9R-d3Yx3iXs=Bg@mail.gmail.com/T/#
Fixes: 1b92b18ec419 ("kconfig: nconf: Ensure null termination where strncpy is used")
Signed-off-by: Shankari Anand <shankari.ak0208@...il.com>
Acked-by: Randy Dunlap <rdunlap@...radead.org>
Tested-by: Randy Dunlap <rdunlap@...radead.org>
---
v1 -> v2: Add closes tag to the report.
Carry-forwarded acked-by and tested-by from previous version
---
 scripts/kconfig/nconf.gui.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/kconfig/nconf.gui.c b/scripts/kconfig/nconf.gui.c
index 475a403ab8ba..7206437e784a 100644
--- a/scripts/kconfig/nconf.gui.c
+++ b/scripts/kconfig/nconf.gui.c
@@ -177,7 +177,7 @@ void fill_window(WINDOW *win, const char *text)
 		const char *line = get_line(text, i);
 		int len = get_line_length(line);
 		strncpy(tmp, line, min(len, x));
-		tmp[sizeof(tmp) - 1] = '\0';
+		tmp[len] = '\0';
 		mvwprintw(win, i, 0, "%s", tmp);
 	}
 }

base-commit: 05adbee3ad528100ab0285c15c91100e19e10138
-- 
2.34.1