Return-Path: From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Wenwen Wang , "David S . Miller" , Sasha Levin Subject: [PATCH AUTOSEL 4.14 59/61] yam: fix a missing-check bug Date: Tue, 16 Oct 2018 00:14:01 -0400 Message-Id: <20181016041403.135678-59-sashal@kernel.org> In-Reply-To: <20181016041403.135678-1-sashal@kernel.org> References: <20181016041403.135678-1-sashal@kernel.org> List-ID: From: Wenwen Wang [ Upstream commit 0781168e23a2fc8dceb989f11fc5b39b3ccacc35 ] In yam_ioctl(), the concrete ioctl command is firstly copied from the user-space buffer 'ifr->ifr_data' to 'ioctl_cmd' and checked through the following switch statement. If the command is not as expected, an error code EINVAL is returned. In the following execution the buffer 'ifr->ifr_data' is copied again in the cases of the switch statement to specific data structures according to what kind of ioctl command is requested. However, after the second copy, no re-check is enforced on the newly-copied command. Given that the buffer 'ifr->ifr_data' is in the user space, a malicious user can race to change the command between the two copies. This way, the attacker can inject inconsistent data and cause undefined behavior. This patch adds a re-check in each case of the switch statement if there is a second copy in that case, to re-check whether the command obtained in the second copy is the same as the one in the first copy. If not, an error code EINVAL will be returned. Signed-off-by: Wenwen Wang Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/net/hamradio/yam.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/net/hamradio/yam.c b/drivers/net/hamradio/yam.c index 7a7c5224a336..16a6e1193912 100644 --- a/drivers/net/hamradio/yam.c +++ b/drivers/net/hamradio/yam.c @@ -980,6 +980,8 @@ static int yam_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd) sizeof(struct yamdrv_ioctl_mcs)); if (IS_ERR(ym)) return PTR_ERR(ym); + if (ym->cmd != SIOCYAMSMCS) + return -EINVAL; if (ym->bitrate > YAM_MAXBITRATE) { kfree(ym); return -EINVAL; @@ -995,6 +997,8 @@ static int yam_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd) if (copy_from_user(&yi, ifr->ifr_data, sizeof(struct yamdrv_ioctl_cfg))) return -EFAULT; + if (yi.cmd != SIOCYAMSCFG) + return -EINVAL; if ((yi.cfg.mask & YAM_IOBASE) && netif_running(dev)) return -EINVAL; /* Cannot change this parameter when up */ if ((yi.cfg.mask & YAM_IRQ) && netif_running(dev)) -- 2.17.1