From ad6008ca4e33e65c0c0799c33ff53cc34e77e755 Mon Sep 17 00:00:00 2001 From: Josh Law Date: Thu, 12 Mar 2026 19:11:43 +0000 Subject: lib/bootconfig: fix snprintf truncation check in xbc_node_compose_key_after() commit 1120a36bb1e9b9e22de75ecb4ef0b998f73a97f1 upstream. snprintf() returns the number of characters that would have been written excluding the NUL terminator. Output is truncated when the return value is >= the buffer size, not just > the buffer size. When ret == size, the current code takes the non-truncated path, advancing buf by ret and reducing size to 0. This is wrong because the output was actually truncated (the last character was replaced by NUL). Fix by using >= so the truncation path is taken correctly. Link: https://lore.kernel.org/all/20260312191143.28719-4-objecting@objecting.org/ Fixes: 76db5a27a827 ("bootconfig: Add Extra Boot Config support") Cc: stable@vger.kernel.org Signed-off-by: Josh Law Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Greg Kroah-Hartman --- lib/bootconfig.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/bootconfig.c b/lib/bootconfig.c index a22e51545fe3..31ac39aeac77 100644 --- a/lib/bootconfig.c +++ b/lib/bootconfig.c @@ -316,7 +316,7 @@ int __init xbc_node_compose_key_after(struct xbc_node *root, depth ? "." : ""); if (ret < 0) return ret; - if (ret > size) { + if (ret >= size) { size = 0; } else { size -= ret; -- cgit v1.2.3