lib/bootconfig: fix off-by-one in xbc_verify_tree() unclosed brace error

__xbc_open_brace() pushes entries with post-increment
(open_brace[brace_index++]), so brace_index always points one past
the last valid entry.  xbc_verify_tree() reads open_brace[brace_index]
to report which brace is unclosed, but this is one past the last
pushed entry and contains stale/zero data, causing the error message
to reference the wrong node.

Use open_brace[brace_index - 1] to correctly identify the unclosed
brace.  brace_index is known to be > 0 here since we are inside the
if (brace_index) guard.

Link: https://lore.kernel.org/all/20260312191143.28719-2-objecting@objecting.org/
Fixes: ead1e19ad905 ("lib/bootconfig: Fix a bug of breaking existing tree nodes")
Cc: stable@vger.kernel.org
Signed-off-by: Josh Law <objecting@objecting.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

diff --git a/lib/bootconfig.c b/lib/bootconfig.c
index 449369a60846189378e9bcc424e937f4c6b4705c..ce25714351d51ad72fb52c8f03f5817a94353c48 100644 (file)
--- a/lib/bootconfig.c
+++ b/lib/bootconfig.c
@@ -802,7 +802,7 @@ static int __init xbc_verify_tree(void)
 
        /* Brace closing */
        if (brace_index) {
-               n = &xbc_nodes[open_brace[brace_index]];
+               n = &xbc_nodes[open_brace[brace_index - 1]];
                return xbc_parse_error("Brace is not closed",
                                        xbc_node_get_data(n));
        }