From: Josh Law Date: Thu, 12 Mar 2026 19:11:43 +0000 (+0000) Subject: lib/bootconfig: fix snprintf truncation check in xbc_node_compose_key_after() X-Git-Tag: v7.0-rc4~3^2~1 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=1120a36bb1e9b9e22de75ecb4ef0b998f73a97f1;p=thirdparty%2Flinux.git lib/bootconfig: fix snprintf truncation check in xbc_node_compose_key_after() 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) --- diff --git a/lib/bootconfig.c b/lib/bootconfig.c index 9c3d59fb96ed..2da049216fe0 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;