Commit 0781168e authored by Wenwen Wang's avatar Wenwen Wang Committed by David S. Miller

yam: fix a missing-check bug

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's avatarWenwen Wang <>
Signed-off-by: default avatarDavid S. Miller <>
parent 33aa8da1
......@@ -966,6 +966,8 @@ 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) {
return -EINVAL;
......@@ -981,6 +983,8 @@ 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))
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