https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=2e950b1edd5615bd145f2eaa99f03db4c998ed15

commit 2e950b1edd5615bd145f2eaa99f03db4c998ed15
Author: Corinna Vinschen <[email protected]>
Date:   Sat Apr 18 17:07:08 2015 +0200

    Try to avoid creating dangerous DENY ACEs
    
            * sec_acl.cc (set_posix_access): Don't create DENY ACEs for USER and
            GROUP entries if they are the same as USER_OBJ or GROUP_OBJ.
    
    Signed-off-by: Corinna Vinschen <[email protected]>

Diff:
---
 winsup/cygwin/ChangeLog  | 5 +++++
 winsup/cygwin/sec_acl.cc | 6 ++++++
 2 files changed, 11 insertions(+)

diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 04bd520..a19a9e9 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,5 +1,10 @@
 2015-04-17  Corinna Vinschen  <[email protected]>
 
+       * sec_acl.cc (set_posix_access): Don't create DENY ACEs for USER and
+       GROUP entries if they are the same as USER_OBJ or GROUP_OBJ.
+
+2015-04-17  Corinna Vinschen  <[email protected]>
+
        * fhandler.h (fhandler_pty_slave::facl): Add prototype.
        * fhandler_tty.cc (fhandler_pty_slave::facl): New method.
        (fhandler_pty_slave::fchown): Fix uid/gid handling.
diff --git a/winsup/cygwin/sec_acl.cc b/winsup/cygwin/sec_acl.cc
index 9336dea..7e65077 100644
--- a/winsup/cygwin/sec_acl.cc
+++ b/winsup/cygwin/sec_acl.cc
@@ -316,6 +316,12 @@ set_posix_access (mode_t attr, uid_t uid, gid_t gid,
               idx < nentries && aclbufp[idx].a_type & check_types;
               ++idx)
            {
+             /* Avoid to create DENY ACEs for the second orrurence of
+                accounts which show up twice, as USER_OBJ and USER, or
+                GROUP_OBJ and GROUP. */
+             if ((aclbufp[idx].a_type & USER && aclsid[idx] == owner)
+                 || (aclbufp[idx].a_type & GROUP && aclsid[idx] == group))
+               continue;
              /* For the rules how to construct the deny access mask, see the
                 comment right at the start of this file. */
              if (aclbufp[idx].a_type & USER_OBJ)

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