netfilter: x_tables: avoid out-of-bounds reads in xt_request_find_{ma…

…tch|target} [ Upstream commit da17c73 ] It looks like syzbot found its way into netfilter territory. Issue here is that @name comes from user space and might not be null terminated. Out-of-bound reads happen, KASAN is not happy. v2 added similar fix for xt_request_find_target(), as Florian advised. Signed-off-by: Eric Dumazet <[email protected]> Reported-by: syzbot <[email protected]> Acked-by: Florian Westphal <[email protected]> Signed-off-by: Pablo Neira Ayuso <[email protected]> Signed-off-by: Sasha Levin <[email protected]>
Noltari · Mar 4, 2018 · 3779fc3 · 3779fc3
1 parent 3ff2aad
commit 3779fc3
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
@@ -209,6 +209,9 @@ xt_request_find_match(uint8_t nfproto, const char *name, uint8_t revision)
 {
 	struct xt_match *match;
 
+	if (strnlen(name, XT_EXTENSION_MAXNAMELEN) == XT_EXTENSION_MAXNAMELEN)
+		return ERR_PTR(-EINVAL);
+
 	match = xt_find_match(nfproto, name, revision);
 	if (IS_ERR(match)) {
 		request_module("%st_%s", xt_prefix[nfproto], name);
@@ -251,6 +254,9 @@ struct xt_target *xt_request_find_target(u8 af, const char *name, u8 revision)
 {
 	struct xt_target *target;
 
+	if (strnlen(name, XT_EXTENSION_MAXNAMELEN) == XT_EXTENSION_MAXNAMELEN)
+		return ERR_PTR(-EINVAL);
+
 	target = xt_find_target(af, name, revision);
 	if (IS_ERR(target)) {
 		request_module("%st_%s", xt_prefix[af], name);