Re: [PATCH net] selinux: add the missing walk_size + len check in selinux_sctp_bind_connect

On Mon, Mar 11, 2019 at 04:11:32PM -0400, Paul Moore wrote:

On Fri, Mar 8, 2019 at 9:47 PM Paul Moore [off-list ref] wrote:

quoted

On Fri, Mar 8, 2019 at 12:08 PM Marcelo Ricardo Leitner
[off-list ref] wrote:

quoted

On Sat, Mar 09, 2019 at 12:07:34AM +0800, Xin Long wrote:

quoted

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]

Fixes: d452930fd3b9 ("selinux: Add SCTP support")
Reported-by: Chunyu Hu <redacted>
Signed-off-by: Xin Long <lucien.xin@gmail.com>

Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>

Thanks, this patch looks good to me.

quoted

Paul, how can we get this into -stable trees? SELinux process may be
different from -net trees.

For patches that warrant inclusion in -stable, I merge them into the
current selinux/stable-X.Y and send it up to Linus once it passes some
basic sanity tests.  Since we're still only half-way through the merge
window, and this is an obvious bug fix, I think this qualifies as
-stable material.

I'm traveling at the moment with not-so-great connectivity, but I'll
get this merged and verified early next week.

FYI, I just merged this into selinux/stable-5.1.  Assuming it tests
okay (and I can't imagine it would cause a regression), I'll send it
to Linus tomorrow.

Thanks Paul.

  Marcelo