[PATCH v4 16/17] lib/bootconfig: check xbc_init_node() return in override path

[Josh Law <objecting@objecting.org>]

The ':=' override path in xbc_parse_kv() calls xbc_init_node() to
re-initialize an existing value node but does not check the return
value.  If xbc_init_node() fails (data offset out of range), parsing
silently continues with stale node data.

Add the missing error check to match the xbc_add_node() call path
which already checks for failure.

In practice, a bootconfig using ':=' to override a value near the
32KB data limit could silently retain the old value, meaning a
security-relevant boot parameter override (e.g., a trace filter or
debug setting) would not take effect as intended.

Signed-off-by: Josh Law <objecting@objecting.org>
---
 lib/bootconfig.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/bootconfig.c b/lib/bootconfig.c
index 038f56689a48..182d9d9bc5a6 100644
--- a/lib/bootconfig.c
+++ b/lib/bootconfig.c
@@ -728,7 +728,8 @@ static int __init xbc_parse_kv(char **k, char *v, int op)
 		if (op == ':') {
 			unsigned short nidx = child->next;
 
-			xbc_init_node(child, v, XBC_VALUE);
+			if (xbc_init_node(child, v, XBC_VALUE) < 0)
+				return xbc_parse_error("Failed to override value", v);
 			child->next = nidx;	/* keep subkeys */
 			goto array;
 		}
-- 
2.34.1