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bootconfig: Skip internal tree sanity checks in kernel

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In xbc_verify_tree(), the loop iterating through all nodes to check that
xbc_nodes[i].next < xbc_node_num and xbc_nodes[i].child < xbc_node_num
is a defensive sanity check against implementation regressions (such
an out-of-bounds index cannot be produced by malformed input).

Running this check in the kernel adds unnecessary boot-time overhead.
Split this check out into xbc_sanity_check_tree() for userspace, so
that it continues to run during userspace bootconfig validation (e.g.
when applying or testing bootconfig with tools/bootconfig), but is
omitted in the kernel to speed up initialization.

Link: https://lore.kernel.org/all/178913600409.248794.12941798680046327623.stgit@devnote2/

Reported-by: Sang-Heon Jeon <ekffu200098@gmail.com>
Closes: https://lore.kernel.org/all/20260905141637.1547429-1-ekffu200098@gmail.com/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Sang-Heon Jeon <ekffu200098@gmail.com>
This commit is contained in:
Masami Hiramatsu (Google) 2026-09-11 23:13:24 +09:00
parent 7871551192
commit e84e60da22
1 changed files with 26 additions and 12 deletions
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38
lib/bootconfig.c
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@ -1005,9 +1005,30 @@ static int __init xbc_close_brace(char **k, char *n)
return __xbc_close_brace(n - 1);
}
#ifndef __KERNEL__
/* Sanity check for regression: node indices must be within bounds */
static int __init xbc_sanity_check_tree(void)
{
int i;
for (i = 0; i < xbc_node_num; i++) {
if (xbc_nodes[i].next >= xbc_node_num) {
return xbc_parse_error("No closing brace",
xbc_node_get_data(xbc_nodes + i));
}
if (xbc_nodes[i].child >= xbc_node_num) {
return xbc_parse_error("Broken child node",
xbc_node_get_data(xbc_nodes + i));
}
}
return 0;
}
#endif
static int __init xbc_verify_tree(void)
{
int i, depth;
int depth;
size_t len, wlen;
struct xbc_node *n, *m;
@ -1024,17 +1045,6 @@ static int __init xbc_verify_tree(void)
return -ENOENT;
}
for (i = 0; i < xbc_node_num; i++) {
if (xbc_nodes[i].next >= xbc_node_num) {
return xbc_parse_error("No closing brace",
xbc_node_get_data(xbc_nodes + i));
}
if (xbc_nodes[i].child >= xbc_node_num) {
return xbc_parse_error("Broken child node",
xbc_node_get_data(xbc_nodes + i));
}
}
/* Key tree limitation check */
n = &xbc_nodes[0];
depth = 1;
@ -1204,6 +1214,10 @@ int __init xbc_init(const char *data, size_t size, const char **emsg, int *epos)
ret = xbc_parse_tree();
if (!ret)
ret = xbc_verify_tree();
#ifndef __KERNEL__
if (!ret)
ret = xbc_sanity_check_tree();
#endif
if (ret < 0) {
if (epos)