Commit 98528072 authored by Wenwen Wang's avatar Wenwen Wang Committed by Greg Kroah-Hartman

net: socket: fix a missing-check bug

[ Upstream commit b6168562c8ce2bd5a30e213021650422e08764dc ]

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: default avatarWenwen Wang <>
Signed-off-by: default avatarDavid S. Miller <>
Signed-off-by: default avatarGreg Kroah-Hartman <>
parent 7fc851d0
...@@ -2760,9 +2760,14 @@ static int ethtool_ioctl(struct net *net, struct compat_ifreq __user *ifr32) ...@@ -2760,9 +2760,14 @@ static int ethtool_ioctl(struct net *net, struct compat_ifreq __user *ifr32)
copy_in_user(&rxnfc->fs.ring_cookie, copy_in_user(&rxnfc->fs.ring_cookie,
&compat_rxnfc->fs.ring_cookie, &compat_rxnfc->fs.ring_cookie,
(void __user *)(&rxnfc->fs.location + 1) - (void __user *)(&rxnfc->fs.location + 1) -
(void __user *)&rxnfc->fs.ring_cookie) || (void __user *)&rxnfc->fs.ring_cookie))
copy_in_user(&rxnfc->rule_cnt, &compat_rxnfc->rule_cnt, return -EFAULT;
sizeof(rxnfc->rule_cnt))) if (ethcmd == ETHTOOL_GRXCLSRLALL) {
if (put_user(rule_cnt, &rxnfc->rule_cnt))
return -EFAULT;
} else if (copy_in_user(&rxnfc->rule_cnt,
return -EFAULT; return -EFAULT;
} }
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