From: Simon Horman Date: Mon, 11 Nov 2024 14:47:51 +0000 (+0000) Subject: netfilter: bpf: Pass string literal as format argument of request_module() X-Git-Tag: v6.13-rc1~135^2~37^2~12 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=8340b0056ac723d04918573761b5d8f979d15a75;p=thirdparty%2Flinux.git netfilter: bpf: Pass string literal as format argument of request_module() Both gcc-14 and clang-18 report that passing a non-string literal as the format argument of request_module() is potentially insecure. E.g. clang-18 says: .../nf_bpf_link.c:46:24: warning: format string is not a string literal (potentially insecure) [-Wformat-security] 46 | err = request_module(mod); | ^~~ .../kmod.h:25:55: note: expanded from macro 'request_module' 25 | #define request_module(mod...) __request_module(true, mod) | ^~~ .../nf_bpf_link.c:46:24: note: treat the string as an argument to avoid this 46 | err = request_module(mod); | ^ | "%s", .../kmod.h:25:55: note: expanded from macro 'request_module' 25 | #define request_module(mod...) __request_module(true, mod) | ^ It is always the case where the contents of mod is safe to pass as the format argument. That is, in my understanding, it never contains any format escape sequences. But, it seems better to be safe than sorry. And, as a bonus, compiler output becomes less verbose by addressing this issue as suggested by clang-18. Compile tested only. Signed-off-by: Simon Horman Reviewed-by: Toke Høiland-Jørgensen Signed-off-by: Pablo Neira Ayuso --- diff --git a/net/netfilter/nf_bpf_link.c b/net/netfilter/nf_bpf_link.c index 3d64a4511fcfd..06b0848447003 100644 --- a/net/netfilter/nf_bpf_link.c +++ b/net/netfilter/nf_bpf_link.c @@ -43,7 +43,7 @@ get_proto_defrag_hook(struct bpf_nf_link *link, hook = rcu_dereference(*ptr_global_hook); if (!hook) { rcu_read_unlock(); - err = request_module(mod); + err = request_module("%s", mod); if (err) return ERR_PTR(err < 0 ? err : -EINVAL);