net: sctp: check proc_dointvec result in proc_sctp_do_auth
authorDaniel Borkmann <dborkman@redhat.com>
Wed, 18 Jun 2014 21:46:31 +0000 (23:46 +0200)
committerDavid S. Miller <davem@davemloft.net>
Fri, 20 Jun 2014 04:30:19 +0000 (21:30 -0700)
When writing to the sysctl field net.sctp.auth_enable, it can well
be that the user buffer we handed over to proc_dointvec() via
proc_sctp_do_auth() handler contains something other than integers.

In that case, we would set an uninitialized 4-byte value from the
stack to net->sctp.auth_enable that can be leaked back when reading
the sysctl variable, and it can unintentionally turn auth_enable
on/off based on the stack content since auth_enable is interpreted
as a boolean.

Fix it up by making sure proc_dointvec() returned sucessfully.

Fixes: b14878ccb7fa ("net: sctp: cache auth_enable per endpoint")
Reported-by: Florian Westphal <fwestpha@redhat.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/sctp/sysctl.c

index cc12162ba091bcef202c9990b162355821c43d04..12c7e01c267711ef19878f6c1da1e66e257ecf7e 100644 (file)
@@ -447,8 +447,7 @@ static int proc_sctp_do_auth(struct ctl_table *ctl, int write,
                tbl.data = &net->sctp.auth_enable;
 
        ret = proc_dointvec(&tbl, write, buffer, lenp, ppos);
-
-       if (write) {
+       if (write && ret == 0) {
                struct sock *sk = net->sctp.ctl_sock;
 
                net->sctp.auth_enable = new_value;