From: Peter Collingbourne pcc@google.com
commit d0efb16294d145d157432feda83877ae9d7cdf37 upstream.
A common implementation of isatty(3) involves calling a ioctl passing a dummy struct argument and checking whether the syscall failed -- bionic and glibc use TCGETS (passing a struct termios), and musl uses TIOCGWINSZ (passing a struct winsize). If the FD is a socket, we will copy sizeof(struct ifreq) bytes of data from the argument and return -EFAULT if that fails. The result is that the isatty implementations may return a non-POSIX-compliant value in errno in the case where part of the dummy struct argument is inaccessible, as both struct termios and struct winsize are smaller than struct ifreq (at least on arm64).
Although there is usually enough stack space following the argument on the stack that this did not present a practical problem up to now, with MTE stack instrumentation it's more likely for the copy to fail, as the memory following the struct may have a different tag.
Fix the problem by adding an early check for whether the ioctl is a valid socket ioctl, and return -ENOTTY if it isn't.
Fixes: 44c02a2c3dc5 ("dev_ioctl(): move copyin/copyout to callers") Link: https://linux-review.googlesource.com/id/I869da6cf6daabc3e4b7b82ac979683ba05... Signed-off-by: Peter Collingbourne pcc@google.com Cc: stable@vger.kernel.org # 4.19 Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/netdevice.h | 4 ++++ net/socket.c | 6 +++++- 2 files changed, 9 insertions(+), 1 deletion(-)
--- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -4012,6 +4012,10 @@ int netdev_rx_handler_register(struct ne void netdev_rx_handler_unregister(struct net_device *dev);
bool dev_valid_name(const char *name); +static inline bool is_socket_ioctl_cmd(unsigned int cmd) +{ + return _IOC_TYPE(cmd) == SOCK_IOC_TYPE; +} int dev_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr, bool *need_copyout); int dev_ifconf(struct net *net, struct ifconf *, int); --- a/net/socket.c +++ b/net/socket.c @@ -1109,7 +1109,7 @@ static long sock_do_ioctl(struct net *ne rtnl_unlock(); if (!err && copy_to_user(argp, &ifc, sizeof(struct ifconf))) err = -EFAULT; - } else { + } else if (is_socket_ioctl_cmd(cmd)) { struct ifreq ifr; bool need_copyout; if (copy_from_user(&ifr, argp, sizeof(struct ifreq))) @@ -1118,6 +1118,8 @@ static long sock_do_ioctl(struct net *ne if (!err && need_copyout) if (copy_to_user(argp, &ifr, sizeof(struct ifreq))) return -EFAULT; + } else { + err = -ENOTTY; } return err; } @@ -3306,6 +3308,8 @@ static int compat_ifr_data_ioctl(struct struct ifreq ifreq; u32 data32;
+ if (!is_socket_ioctl_cmd(cmd)) + return -ENOTTY; if (copy_from_user(ifreq.ifr_name, u_ifreq32->ifr_name, IFNAMSIZ)) return -EFAULT; if (get_user(data32, &u_ifreq32->ifr_data))