Re: [PATCH] Cygwin: get_posix_access: avoid negative subscript

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

Hi Ken,

On Aug 26 17:43, Ken Brown wrote:
> Don't refer to lacl[pos] unless we know that pos >= 0.

I'm not sure this is entirely right.  Moving the assignment to
class_perm/def_class_perm into the previous if makes sense, but the
bools has_class_perm and has_def_class_perm should be set no matter
what, to indicate that class perms had been specified.

Either way, does this solve a real-world problem?  If so, a pointer
or a short description would be nice.


Thanks,
Corinna


> ---
>  winsup/cygwin/sec_acl.cc | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/winsup/cygwin/sec_acl.cc b/winsup/cygwin/sec_acl.cc
> index 933bfa69d..67749d7b1 100644
> --- a/winsup/cygwin/sec_acl.cc
> +++ b/winsup/cygwin/sec_acl.cc
> @@ -807,9 +807,9 @@ get_posix_access (PSECURITY_DESCRIPTOR psd,
>  			  lacl[pos].a_id = ACL_UNDEFINED_ID;
>  			  lacl[pos].a_perm = CYG_ACE_MASK_TO_POSIX (ace->Mask);
>  			  aclsid[pos] = well_known_null_sid;
> +			  has_class_perm = true;
> +			  class_perm = lacl[pos].a_perm;
>  			}
> -		      has_class_perm = true;
> -		      class_perm = lacl[pos].a_perm;
>  		    }
>  		  if (ace->Header.AceFlags & SUB_CONTAINERS_AND_OBJECTS_INHERIT)
>  		    {
> @@ -820,9 +820,9 @@ get_posix_access (PSECURITY_DESCRIPTOR psd,
>  			  lacl[pos].a_id = ACL_UNDEFINED_ID;
>  			  lacl[pos].a_perm = CYG_ACE_MASK_TO_POSIX (ace->Mask);
>  			  aclsid[pos] = well_known_null_sid;
> +			  has_def_class_perm = true;
> +			  def_class_perm = lacl[pos].a_perm;
>  			}
> -		      has_def_class_perm = true;
> -		      def_class_perm = lacl[pos].a_perm;
>  		    }
>  		}
>  	    }
> -- 
> 2.21.0

-- 
Corinna Vinschen
Cygwin Maintainer

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