image-sig: Ensure that hashed-nodes is null-terminated
A specially crafted FIT image leads to memory corruption in the stack
when using the verified boot feature. The function fit_config_check_sig
has a logic error that makes it possible to write past the end of the
stack allocated array node_inc. This could potentially be used to bypass
the signature check when using verified boot.
This change ensures that the number of strings is correct when counted.
Signed-off-by: Konrad Beckmann <konrad.beckmann@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/common/image-sig.c b/common/image-sig.c
index 5a269d3..5d860e1 100644
--- a/common/image-sig.c
+++ b/common/image-sig.c
@@ -334,6 +334,11 @@
return -1;
}
+ if (prop && prop_len > 0 && prop[prop_len - 1] != '\0') {
+ *err_msgp = "hashed-nodes property must be null-terminated";
+ return -1;
+ }
+
/* Add a sanity check here since we are using the stack */
if (count > IMAGE_MAX_HASHED_NODES) {
*err_msgp = "Number of hashed nodes exceeds maximum";