[PATCH 5.0 154/238] selinux: add the missing walk_size + len check in selinux_sctp_bind_connect

[Greg Kroah-Hartman]

5.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Xin Long <lucien.xin@xxxxxxxxx>

commit 292c997a1970f8d1e1dfa354ed770a22f7b5a434 upstream.

As does in __sctp_connect(), when checking addrs in a while loop, after
get the addr len according to sa_family, it's necessary to do the check
walk_size + af->sockaddr_len > addrs_size to make sure it won't access
an out-of-bounds addr.

The same thing is needed in selinux_sctp_bind_connect(), otherwise an
out-of-bounds issue can be triggered:

  [14548.772313] BUG: KASAN: slab-out-of-bounds in selinux_sctp_bind_connect+0x1aa/0x1f0
  [14548.927083] Call Trace:
  [14548.938072]  dump_stack+0x9a/0xe9
  [14548.953015]  print_address_description+0x65/0x22e
  [14548.996524]  kasan_report.cold.6+0x92/0x1a6
  [14549.015335]  selinux_sctp_bind_connect+0x1aa/0x1f0
  [14549.036947]  security_sctp_bind_connect+0x58/0x90
  [14549.058142]  __sctp_setsockopt_connectx+0x5a/0x150 [sctp]
  [14549.081650]  sctp_setsockopt.part.24+0x1322/0x3ce0 [sctp]

Cc: stable@xxxxxxxxxxxxxxx
Fixes: d452930fd3b9 ("selinux: Add SCTP support")
Reported-by: Chunyu Hu <chuhu@xxxxxxxxxx>
Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>
Signed-off-by: Paul Moore <paul@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 security/selinux/hooks.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -5120,6 +5120,9 @@ static int selinux_sctp_bind_connect(str
 			return -EINVAL;
 		}
 
+		if (walk_size + len > addrlen)
+			return -EINVAL;
+
 		err = -EINVAL;
 		switch (optname) {
 		/* Bind checks */