region: Introduce region_create() functions

We introduce two new functions to create region objects. They allow us
to check for integer overflows (region_create_untrusted()) or assert
their absence (region_create()).

This fixes potential overflows in region_overlap() checks in SMI
handlers, where we would wrongfully report MMIO as *not* overlapping
SMRAM.

Also, two cases of strtol() in parse_region() (cbfstool),  where the
results were implicitly converted to `size_t`, are replaced with the
unsigned strtoul().

FIT payload support is left out, as it doesn't use the region API
(only the struct).

Change-Id: I4ae3e6274c981c9ab4fb1263c2a72fa68ef1c32b
Ticket: https://ticket.coreboot.org/issues/522
Found-by: Vadim Zaliva <lord@digamma.ai>
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79905
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

1 files changed, 20 insertions, 8 deletions

diff --git a/util/cbfstool/cse_serger.c b/util/cbfstool/cse_serger.c
index f53b3904af..006a01e9be 100644
--- a/util/cbfstool/cse_serger.c
+++ b/util/cbfstool/cse_serger.c
@@ -820,15 +820,22 @@ static int cmd_add(void)
 	return 0;
 }
 
-static void parse_region(struct region *r, char *arg)
+static int parse_region(struct region *r, char *arg)
 {
 	char *tok;
 
 	tok = strtok(arg, ":");
-	r->offset = strtol(tok, NULL, 0);
+	unsigned long offset = strtoul(tok, NULL, 0);
 
 	tok = strtok(NULL, ":");
-	r->size = strtol(tok, NULL, 0);
+	unsigned long size = strtoul(tok, NULL, 0);
+
+	if (region_create_untrusted(r, offset, size) != CB_SUCCESS) {
+		ERROR("Invalid region: %lx:%lx\n", offset, size);
+		return -1;
+	}
+
+	return 0;
 }
 
 static struct command {
@@ -991,19 +998,24 @@ int main(int argc, char **argv)
 				params.partition_type = atoi(optarg);
 				break;
 			case LONGOPT_BP1:
-				parse_region(&params.layout_regions[BP1], optarg);
+				if (parse_region(&params.layout_regions[BP1], optarg))
+					return 1;
 				break;
 			case LONGOPT_BP2:
-				parse_region(&params.layout_regions[BP2], optarg);
+				if (parse_region(&params.layout_regions[BP2], optarg))
+					return 1;
 				break;
 			case LONGOPT_BP3:
-				parse_region(&params.layout_regions[BP3], optarg);
+				if (parse_region(&params.layout_regions[BP3], optarg))
+					return 1;
 				break;
 			case LONGOPT_BP4:
-				parse_region(&params.layout_regions[BP4], optarg);
+				if (parse_region(&params.layout_regions[BP4], optarg))
+					return 1;
 				break;
 			case LONGOPT_DATA:
-				parse_region(&params.layout_regions[DP], optarg);
+				if (parse_region(&params.layout_regions[DP], optarg))
+					return 1;
 				break;
 			case LONGOPT_BP1_FILE:
 				params.layout_files[BP1] = optarg;