[PATCH 5.15 289/570] lib/bootconfig: check xbc_init_node() return in override path

Greg Kroah-Hartman
2026-04-13T16:30:31Z

From: Josh Law <objecting@objecting.org>

[ Upstream commit bb288d7d869e86d382f35a0e26242c5ccb05ca82 ]

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.

Link: https://lore.kernel.org/all/20260318155847.78065-2-objecting@objecting.org/

Fixes: e5efaeb8a8f5 ("bootconfig: Support mixing a value and subkeys under a key")
Signed-off-by: Josh Law <objecting@objecting.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
lib/bootconfig.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/bootconfig.c b/lib/bootconfig.c
index 0579a93cb163e..9873c6372adca 100644
--- a/lib/bootconfig.c
+++ b/lib/bootconfig.c
@@ -646,7 +646,8 @@ 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;
}
--
2.51.0