[PATCH] libsepol: Add overflow checks when linking file and netfilter contexts

Use __builtin_add_overflow() when calculating the total length
of all the file and netfilter contexts.

Signed-off-by: James Carter <[email protected]>
---
 libsepol/src/module.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/libsepol/src/module.c b/libsepol/src/module.c
index 5fcf5870..8aaa693d 100644
--- a/libsepol/src/module.c
+++ b/libsepol/src/module.c
@@ -249,7 +249,8 @@ static int link_file_contexts(sepol_module_package_t *base,
 
 	fc_len = base->file_contexts_len;
 	for (i = 0; i < num_modules; i++) {
-		fc_len += modules[i]->file_contexts_len;
+		if (__builtin_add_overflow(fc_len, modules[i]->file_contexts_len, &fc_len))
+			return -1;
 	}
 
 	if ((s = (char *)realloc(base->file_contexts, fc_len)) == NULL) {
@@ -281,7 +282,8 @@ static int link_netfilter_contexts(sepol_module_package_t *base,
 
 	base_nc_len = base->netfilter_contexts_len;
 	for (i = 0; i < num_modules; i++) {
-		base_nc_len += modules[i]->netfilter_contexts_len;
+		if (__builtin_add_overflow(base_nc_len, modules[i]->netfilter_contexts_len, &base_nc_len))
+			return -1;
 	}
 
 	if ((base_context = (char *)realloc(base->netfilter_contexts,
-- 
2.55.0