diff options
authorWenwen Wang <wang6495@umn.edu>2018-10-18 09:36:46 -0500
committerDavid S. Miller <davem@davemloft.net>2018-10-18 16:43:06 -0700
commitb6168562c8ce2bd5a30e213021650422e08764dc (patch)
parent3c53ed8fef6881a864f0ee8240ed2793ef73ad0d (diff)
net: socket: fix a missing-check bug
In ethtool_ioctl(), the ioctl command 'ethcmd' is checked through a switch statement to see whether it is necessary to pre-process the ethtool structure, because, as mentioned in the comment, the structure ethtool_rxnfc is defined with padding. If yes, a user-space buffer 'rxnfc' is allocated through compat_alloc_user_space(). One thing to note here is that, if 'ethcmd' is ETHTOOL_GRXCLSRLALL, the size of the buffer 'rxnfc' is partially determined by 'rule_cnt', which is actually acquired from the user-space buffer 'compat_rxnfc', i.e., 'compat_rxnfc->rule_cnt', through get_user(). After 'rxnfc' is allocated, the data in the original user-space buffer 'compat_rxnfc' is then copied to 'rxnfc' through copy_in_user(), including the 'rule_cnt' field. However, after this copy, no check is re-enforced on 'rxnfc->rule_cnt'. So it is possible that a malicious user race to change the value in the 'compat_rxnfc->rule_cnt' between these two copies. Through this way, the attacker can bypass the previous check on 'rule_cnt' and inject malicious data. This can cause undefined behavior of the kernel and introduce potential security risk. This patch avoids the above issue via copying the value acquired by get_user() to 'rxnfc->rule_cn', if 'ethcmd' is ETHTOOL_GRXCLSRLALL. Signed-off-by: Wenwen Wang <wang6495@umn.edu> Signed-off-by: David S. Miller <davem@davemloft.net>
1 files changed, 8 insertions, 3 deletions
diff --git a/net/socket.c b/net/socket.c
index 01f3f8f32d6f..390a8ecef4bf 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2875,9 +2875,14 @@ static int ethtool_ioctl(struct net *net, struct compat_ifreq __user *ifr32)
(void __user *)(&rxnfc->fs.location + 1) -
- (void __user *)&rxnfc->fs.ring_cookie) ||
- copy_in_user(&rxnfc->rule_cnt, &compat_rxnfc->rule_cnt,
- sizeof(rxnfc->rule_cnt)))
+ (void __user *)&rxnfc->fs.ring_cookie))
+ return -EFAULT;
+ if (ethcmd == ETHTOOL_GRXCLSRLALL) {
+ if (put_user(rule_cnt, &rxnfc->rule_cnt))
+ return -EFAULT;
+ } else if (copy_in_user(&rxnfc->rule_cnt,
+ &compat_rxnfc->rule_cnt,
+ sizeof(rxnfc->rule_cnt)))
return -EFAULT;