From: Masami Hiramatsu (Google) <[email protected]> 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. Reported-by: Sang-Heon Jeon <[email protected]> Closes: https://lore.kernel.org/all/[email protected]/ Signed-off-by: Masami Hiramatsu (Google) <[email protected]> Reviewed-by: Sang-Heon Jeon <[email protected]> --- lib/bootconfig.c | 38 ++++++++++++++++++++++++++------------ 1 file changed, 26 insertions(+), 12 deletions(-) diff --git a/lib/bootconfig.c b/lib/bootconfig.c index 61cae6d6e3f8..20b3d6e78fea 100644 --- a/lib/bootconfig.c +++ b/lib/bootconfig.c @@ -1003,9 +1003,30 @@ 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; @@ -1022,17 +1043,6 @@ 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; @@ -1203,6 +1213,10 @@ 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)
