netdev - [PATCH FINAL] SCTP: fix race between sctp_bind_addr_free() and sctp_bind_addr

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <4DD575A1.4080405@gmail.com>
Date:	Thu, 19 May 2011 21:55:13 +0200
From:	Jacek Luczak <difrost.kernel@...il.com>
To:	David Miller <davem@...emloft.net>
CC:	vladislav.yasevich@...com, eric.dumazet@...il.com,
	netdev@...r.kernel.org
Subject: [PATCH FINAL] SCTP: fix race between sctp_bind_addr_free() and sctp_bind_addr_conflict()

During the sctp_close() call, we do not use rcu primitives to
destroy the address list attached to the endpoint.  At the same
time, we do the removal of addresses from this list before
attempting to remove the socket from the port hash

As a result, it is possible for another process to find the socket
in the port hash that is in the process of being closed.  It then
proceeds to traverse the address list to find the conflict, only
to have that address list suddenly disappear without rcu() critical
section.

Fix issue by closing address list removal inside RCU critical
section.

Race can result in a kernel crash with general protection fault or
kernel NULL pointer dereference:

kernel: general protection fault: 0000 [#1] SMP
kernel: RIP: 0010:[<ffffffffa02f3dde>]  [<ffffffffa02f3dde>] sctp_bind_addr_conflict+0x64/0x82 [sctp]
kernel: Call Trace:
kernel:  [<ffffffffa02f415f>] ? sctp_get_port_local+0x17b/0x2a3 [sctp]
kernel:  [<ffffffffa02f3d45>] ? sctp_bind_addr_match+0x33/0x68 [sctp]
kernel:  [<ffffffffa02f4416>] ? sctp_do_bind+0xd3/0x141 [sctp]
kernel:  [<ffffffffa02f5030>] ? sctp_bindx_add+0x4d/0x8e [sctp]
kernel:  [<ffffffffa02f5183>] ? sctp_setsockopt_bindx+0x112/0x4a4 [sctp]
kernel:  [<ffffffff81089e82>] ? generic_file_aio_write+0x7f/0x9b
kernel:  [<ffffffffa02f763e>] ? sctp_setsockopt+0x14f/0xfee [sctp]
kernel:  [<ffffffff810c11fb>] ? do_sync_write+0xab/0xeb
kernel:  [<ffffffff810e82ab>] ? fsnotify+0x239/0x282
kernel:  [<ffffffff810c2462>] ? alloc_file+0x18/0xb1
kernel:  [<ffffffff8134a0b1>] ? compat_sys_setsockopt+0x1a5/0x1d9
kernel:  [<ffffffff8134aaf1>] ? compat_sys_socketcall+0x143/0x1a4
kernel:  [<ffffffff810467dc>] ? sysenter_dispatch+0x7/0x32

Signed-off-by: Jacek Luczak <luczak.jacek@...il.com>
Acked-by: Vlad Yasevich <vladislav.yasevich@...com>
CC: Eric Dumazet <eric.dumazet@...il.com>

---
 net/sctp/bind_addr.c |   10 ++++------
 1 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/net/sctp/bind_addr.c b/net/sctp/bind_addr.c
index faf71d1..6150ac5 100644
--- a/net/sctp/bind_addr.c
+++ b/net/sctp/bind_addr.c
@@ -140,14 +140,12 @@ void sctp_bind_addr_init(struct sctp_bind_addr *bp, __u16 port)
 /* Dispose of the address list. */
 static void sctp_bind_addr_clean(struct sctp_bind_addr *bp)
 {
-	struct sctp_sockaddr_entry *addr;
-	struct list_head *pos, *temp;
+	struct sctp_sockaddr_entry *addr, *temp;
 
 	/* Empty the bind address list. */
-	list_for_each_safe(pos, temp, &bp->address_list) {
-		addr = list_entry(pos, struct sctp_sockaddr_entry, list);
-		list_del(pos);
-		kfree(addr);
+	list_for_each_entry_safe(addr, temp, &bp->address_list, list) {
+		list_del_rcu(&addr->list);
+		call_rcu(&addr->rcu, sctp_local_addr_free);
 		SCTP_DBG_OBJCNT_DEC(addr);
 	}
 }

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html