[PATCH v2 1/3] lib/bootconfig: fix off-by-one in xbc_verify_tree() unclosed brace error

[Josh Law <hlcj1234567@gmail.com>]

From: Josh Law <objecting@objecting.org>

__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.

Signed-off-by: Josh Law <objecting@objecting.org>
---
 lib/bootconfig.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/bootconfig.c b/lib/bootconfig.c
index 2bcd5c2aa87e..a1e6a2e14b01 100644
--- 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));
 	}
-- 
2.34.1