4.9-stable review patch. If anyone has any objections, please let me know.
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From: Wenwen Wang wang6495@umn.edu
[ 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: Wenwen Wang wang6495@umn.edu Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/socket.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
--- a/net/socket.c +++ b/net/socket.c @@ -2774,9 +2774,14 @@ static int ethtool_ioctl(struct net *net copy_in_user(&rxnfc->fs.ring_cookie, &compat_rxnfc->fs.ring_cookie, (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; }