From c6f33e05225696fee3c901b7526b80f31848454e Mon Sep 17 00:00:00 2001 From: Xin Long Date: Sun, 3 Mar 2019 17:54:55 +0800 Subject: [PATCH] sctp: call sctp_auth_init_hmacs() in sctp_sock_migrate() New ep's auth_hmacs should be set if old ep's is set, in case that net->sctp.auth_enable has been changed to 0 by users and new ep's auth_hmacs couldn't be set in sctp_endpoint_init(). It can even crash kernel by doing: 1. on server: sysctl -w net.sctp.auth_enable=1, sysctl -w net.sctp.addip_enable=1, sysctl -w net.sctp.addip_noauth_enable=0, listen() on server, sysctl -w net.sctp.auth_enable=0. 2. on client: connect() to server. 3. on server: accept() the asoc, sysctl -w net.sctp.auth_enable=1. 4. on client: send() asconf packet to server. The call trace: [ 245.280251] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 [ 245.286872] RIP: 0010:sctp_auth_calculate_hmac+0xa3/0x140 [sctp] [ 245.304572] Call Trace: [ 245.305091] [ 245.311287] sctp_sf_authenticate+0x110/0x160 [sctp] [ 245.312311] sctp_sf_eat_auth+0xf2/0x230 [sctp] [ 245.313249] sctp_do_sm+0x9a/0x2d0 [sctp] [ 245.321483] sctp_assoc_bh_rcv+0xed/0x1a0 [sctp] [ 245.322495] sctp_rcv+0xa66/0xc70 [sctp] It's because the old ep->auth_hmacs wasn't copied to the new ep while ep->auth_hmacs is used in sctp_auth_calculate_hmac() when processing the incoming auth chunks, and it should have been done when migrating sock. Reported-by: Ying Xu Signed-off-by: Xin Long Acked-by: Neil Horman Signed-off-by: David S. Miller --- net/sctp/socket.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 44f2acb3d433..6140471efd4b 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -9225,6 +9225,16 @@ static int sctp_sock_migrate(struct sock *oldsk, struct sock *newsk, if (err) return err; + /* New ep's auth_hmacs should be set if old ep's is set, in case + * that net->sctp.auth_enable has been changed to 0 by users and + * new ep's auth_hmacs couldn't be set in sctp_endpoint_init(). + */ + if (oldsp->ep->auth_hmacs) { + err = sctp_auth_init_hmacs(newsp->ep, GFP_KERNEL); + if (err) + return err; + } + /* Move any messages in the old socket's receive queue that are for the * peeled off association to the new socket's receive queue. */ -- 2.20.1