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authorAlexey Izbyshev <izbyshev@ispras.ru>2023-02-28 03:11:17 +0300
committerRich Felker <dalias@aerifal.cx>2023-02-28 11:48:05 -0500
commitc499c1084eaccd83e4b6e60883a5d92df0202c5e (patch)
tree60d31455d5424a07c8bde0c41001c6b2865c0616
parent523d9b965df65bd3ad52863abc817724d7a35f32 (diff)
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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.
-rw-r--r--src/network/accept4.c4
1 files changed, 4 insertions, 0 deletions
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)