leaking_addresses: add timeout on file read

Currently script can stall if we read certain files (like
/proc/kmsg). While we have a mechanism to skip these files once they are
discovered it would be nice to not stall on as yet undiscovered files of
this kind.

Set a timer before each file is parsed, warn user if timer expires.

Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tobin C. Harding <me@tobin.cc>

diff --git a/scripts/leaking_addresses.pl b/scripts/leaking_addresses.pl
index 1d6ab7f1b10c99db3e3cd43b72f9f19bcb8ba26c..6efd1fdb7d2556ca03216599f510af25c28f9127 100755 (executable)
--- a/scripts/leaking_addresses.pl
+++ b/scripts/leaking_addresses.pl
@@ -29,6 +29,9 @@ my $V = '0.01';
 # Directories to scan.
 my @DIRS = ('/proc', '/sys');
 
+# Timer for parsing each file, in seconds.
+my $TIMEOUT = 10;
+
 # Script can only grep for kernel addresses on the following architectures. If
 # your architecture is not listed here and has a grep'able kernel address please
 # consider submitting a patch.
@@ -284,6 +287,23 @@ sub skip_parse
        return skip($path, \@skip_parse_files_abs, \@skip_parse_files_any);
 }
 
+sub timed_parse_file
+{
+       my ($file) = @_;
+
+       eval {
+               local $SIG{ALRM} = sub { die "alarm\n" }; # NB: \n required.
+               alarm $TIMEOUT;
+               parse_file($file);
+               alarm 0;
+       };
+
+       if ($@) {
+               die unless $@ eq "alarm\n";     # Propagate unexpected errors.
+               printf STDERR "timed out parsing: %s\n", $file;
+       }
+}
+
 sub parse_file
 {
        my ($file) = @_;
@@ -335,7 +355,7 @@ sub walk
                        if (-d $path) {
                                push @dirs, $path;
                        } else {
-                               parse_file($path);
+                               timed_parse_file($path);
                        }
                }
        }