checkpatch: improve octal permissions tests

Add world writable permissions tests for the various functions like
debugfs etc...

Add $String type for $FuncArg so that string constants are matched.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -298,6 +298,7 @@ our $Binary	= qr{(?i)0b[01]+$Int_type?};
 our $Hex	= qr{(?i)0x[0-9a-f]+$Int_type?};
 our $Int	= qr{[0-9]+$Int_type?};
 our $Octal	= qr{0[0-7]+$Int_type?};
+our $String	= qr{"[X\t]*"};
 our $Float_hex	= qr{(?i)0x[0-9a-f]+p-?[0-9]+[fl]?};
 our $Float_dec	= qr{(?i)(?:[0-9]+\.[0-9]*|[0-9]*\.[0-9]+)(?:e-?[0-9]+)?[fl]?};
 our $Float_int	= qr{(?i)[0-9]+e-?[0-9]+[fl]?};
@@ -517,7 +518,7 @@ our $Typecast	= qr{\s*(\(\s*$NonptrType\s*\)){0,1}\s*};
 
 our $balanced_parens = qr/(\((?:[^\(\)]++|(?-1))*\))/;
 our $LvalOrFunc	= qr{((?:[\&\*]\s*)?$Lval)\s*($balanced_parens{0,1})\s*};
-our $FuncArg = qr{$Typecast{0,1}($LvalOrFunc|$Constant)};
+our $FuncArg = qr{$Typecast{0,1}($LvalOrFunc|$Constant|$String)};
 
 our $declaration_macros = qr{(?x:
 	(?:$Storage\s+)?(?:[A-Z_][A-Z0-9]*_){0,2}(?:DEFINE|DECLARE)(?:_[A-Z0-9]+){1,2}\s*\(|
@@ -5261,6 +5262,9 @@ sub process {
 					     length($val) ne 4)) {
 						ERROR("NON_OCTAL_PERMISSIONS",
 						      "Use 4 digit octal (0777) not decimal permissions\n" . $herecurr);
+					} elsif ($val =~ /^$Octal$/ && (oct($val) & 02)) {
+						ERROR("EXPORTED_WORLD_WRITABLE",
+						      "Exporting writable files is usually an error. Consider more restrictive permissions.\n" . $herecurr);
 					}
 				}
 			}