From c499c1084eaccd83e4b6e60883a5d92df0202c5e Mon Sep 17 00:00:00 2001 From: Alexey Izbyshev Date: Tue, 28 Feb 2023 03:11:17 +0300 Subject: accept4: don't fall back to accept if we got unknown flags accept4 emulation via accept ignores unknown flags, so it can spuriously succeed instead of failing (or succeed without doing the action implied by an unknown flag if it's added in a future kernel). Worse, unknown flags trigger the fallback code even on modern kernels if the real accept4 syscall returns EINVAL, because this is indistinguishable from socketcall returning EINVAL due to lack of accept4 support. Fix this by always failing with EINVAL if unknown flags are present and the syscall is missing or failed with EINVAL. --- src/network/accept4.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/src/network/accept4.c b/src/network/accept4.c index 59ab1726..765a38ed 100644 --- a/src/network/accept4.c +++ b/src/network/accept4.c @@ -9,6 +9,10 @@ int accept4(int fd, struct sockaddr *restrict addr, socklen_t *restrict len, int if (!flg) return accept(fd, addr, len); int ret = socketcall_cp(accept4, fd, addr, len, flg, 0, 0); if (ret>=0 || (errno != ENOSYS && errno != EINVAL)) return ret; + if (flg & ~(SOCK_CLOEXEC|SOCK_NONBLOCK)) { + errno = EINVAL; + return -1; + } ret = accept(fd, addr, len); if (ret<0) return ret; if (flg & SOCK_CLOEXEC) -- cgit 1.4.1