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Groups > linux.kernel > #1540095

Re: CVE-2016-7097 causes acl leak

From Cong Wang <xiyou.wangcong@gmail.com>
Newsgroups linux.kernel
Subject Re: CVE-2016-7097 causes acl leak
Date 2016-12-12 01:40 +0100
Message-ID <sNmOS-5RV-7@gated-at.bofh.it> (permalink)
References <sL55L-7o6-23@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Mon, Dec 5, 2016 at 9:16 AM, Mark Salyzyn <salyzyn@android.com> wrote:
> Commit 073931017b49d9458aa351605b43a7e34598caef has several occurrences of
> an acl leak.
>
> posix_acl_update_mode(inose, &mode, &acl);
>
> . . .
>
> posix_acl_release(acl);
>
>
> acl is NULLed in posix_acl_update_mode to signal caller to not update the
> acl; but because it is nulled, it is never released.

I think you blame the wrong commit, this leak exists before that commit.
Looks like we should just release it before NULL'ing.

diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 5955220..edd862a 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -648,8 +648,10 @@ int posix_acl_update_mode(struct inode *inode,
umode_t *mode_p,
        error = posix_acl_equiv_mode(*acl, &mode);
        if (error < 0)
                return error;
-       if (error == 0)
+       if (error == 0) {
+               posix_acl_release(*acl);
                *acl = NULL;
+       }
        if (!in_group_p(inode->i_gid) &&
            !capable_wrt_inode_uidgid(inode, CAP_FSETID))
                mode &= ~S_ISGID;

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Thread

CVE-2016-7097 causes acl leak Mark Salyzyn <salyzyn@android.com> - 2016-12-05 18:20 +0100
  Re: CVE-2016-7097 causes acl leak Greg KH <gregkh@linuxfoundation.org> - 2016-12-11 21:40 +0100
  Re: CVE-2016-7097 causes acl leak Cong Wang <xiyou.wangcong@gmail.com> - 2016-12-12 01:40 +0100
    Re: CVE-2016-7097 causes acl leak Jan Kara <jack@suse.cz> - 2016-12-12 11:50 +0100
      Re: CVE-2016-7097 causes acl leak Cong Wang <xiyou.wangcong@gmail.com> - 2016-12-12 22:20 +0100
    Re: CVE-2016-7097 causes acl leak Mark Salyzyn <salyzyn@android.com> - 2016-12-13 01:30 +0100
      Re: CVE-2016-7097 causes acl leak Cong Wang <xiyou.wangcong@gmail.com> - 2016-12-13 07:30 +0100
        Re: CVE-2016-7097 causes acl leak Jan Kara <jack@suse.cz> - 2016-12-13 12:30 +0100
          Re: CVE-2016-7097 causes acl leak Cong Wang <xiyou.wangcong@gmail.com> - 2016-12-14 01:00 +0100
        Re: CVE-2016-7097 causes acl leak Mark Salyzyn <salyzyn@android.com> - 2016-12-13 17:00 +0100
          Re: CVE-2016-7097 causes acl leak Jan Kara <jack@suse.cz> - 2016-12-13 17:10 +0100
        Re: CVE-2016-7097 causes acl leak Mark Salyzyn <salyzyn@android.com> - 2016-12-14 00:50 +0100
          Re: CVE-2016-7097 causes acl leak Greg KH <gregkh@linuxfoundation.org> - 2016-12-14 01:10 +0100
            Re: CVE-2016-7097 causes acl leak Mark Salyzyn <salyzyn@android.com> - 2016-12-14 21:30 +0100
              Re: CVE-2016-7097 causes acl leak Greg KH <gregkh@linuxfoundation.org> - 2016-12-15 00:40 +0100
                Re: CVE-2016-7097 causes acl leak Mark Salyzyn <salyzyn@android.com> - 2016-12-15 16:30 +0100
                Re: CVE-2016-7097 causes acl leak Jan Kara <jack@suse.cz> - 2016-12-15 17:40 +0100
      Re: CVE-2016-7097 causes acl leak Jan Kara <jack@suse.cz> - 2016-12-13 12:20 +0100

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