If fchmod(2) is called on an AF_LOCAL or AF_UNIX socket that is not a socket file, the current code calls fhandler_disk_file::fchmod in most cases. The latter expects to be operating on a disk file and uses the socket's io_handle, which is not a file handle.
Fix this by calling fhandler_disk_file::fchmod only if the fhandler_socket object is a file (determined by testing dev().isfs()). --- winsup/cygwin/fhandler_socket_local.cc | 6 +++++- winsup/cygwin/fhandler_socket_unix.cc | 8 +++++--- 2 files changed, 10 insertions(+), 4 deletions(-) diff --git a/winsup/cygwin/fhandler_socket_local.cc b/winsup/cygwin/fhandler_socket_local.cc index 5ca6d8550..d1faa079a 100644 --- a/winsup/cygwin/fhandler_socket_local.cc +++ b/winsup/cygwin/fhandler_socket_local.cc @@ -710,8 +710,12 @@ fhandler_socket_local::fstatvfs (struct statvfs *sfs) int fhandler_socket_local::fchmod (mode_t newmode) { - if (get_sun_path () && get_sun_path ()[0] == '\0') + if (!dev ().isfs ()) + /* fchmod called on a socket. */ return fhandler_socket_wsock::fchmod (newmode); + + /* chmod on a socket file. [We won't get here if fchmod is called + on a socket opened w/ O_PATH.] */ fhandler_disk_file fh (pc); fh.get_device () = FH_FS; return fh.fchmod (S_IFSOCK | adjust_socket_file_mode (newmode)); diff --git a/winsup/cygwin/fhandler_socket_unix.cc b/winsup/cygwin/fhandler_socket_unix.cc index 06db929ed..e08e9bdd9 100644 --- a/winsup/cygwin/fhandler_socket_unix.cc +++ b/winsup/cygwin/fhandler_socket_unix.cc @@ -2374,10 +2374,12 @@ fhandler_socket_unix::fstatvfs (struct statvfs *sfs) int fhandler_socket_unix::fchmod (mode_t newmode) { - if (sun_path () - && (sun_path ()->un_len <= (socklen_t) sizeof (sa_family_t) - || sun_path ()->un.sun_path[0] == '\0')) + if (!dev ().isfs ()) + /* fchmod called on a socket. */ return fhandler_socket::fchmod (newmode); + + /* chmod on a socket file. [We won't get here if fchmod is called + on a socket opened w/ O_PATH.] */ fhandler_disk_file fh (pc); fh.get_device () = FH_FS; /* Kludge: Don't allow to remove read bit on socket files for -- 2.30.0