From 24599e61b7552673dd85971cf5a35369cd8c119e Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Wed, 18 Jun 2014 23:46:31 +0200 Subject: [PATCH] net: sctp: check proc_dointvec result in proc_sctp_do_auth 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 Signed-off-by: Daniel Borkmann Acked-by: Neil Horman Acked-by: Vlad Yasevich Signed-off-by: David S. Miller --- net/sctp/sysctl.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c index cc12162ba091..12c7e01c2677 100644 --- a/net/sctp/sysctl.c +++ b/net/sctp/sysctl.c @@ -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; -- 2.20.1