grep: Fix out of bounds StringView indexing

This is another case of out of bounds indexing exposed by 13406b8.

1 files changed, 4 insertions, 2 deletions

diff --git a/Userland/Utilities/grep.cpp b/Userland/Utilities/grep.cpp
index 67c7cf724a..0fb9fe8188 100644
--- a/Userland/Utilities/grep.cpp
+++ b/Userland/Utilities/grep.cpp
@@ -175,12 +175,14 @@ ErrorOr<int> serenity_main(Main::Arguments args)
                         out(colored_output ? "\x1B[35m{}:\x1B[0m"sv : "{}:"sv, line_number);
 
                     for (auto& match : result.matches) {
+                        auto pre_match_length = match.global_offset - last_printed_char_pos;
                         out(colored_output ? "{}\x1B[32m{}\x1B[0m"sv : "{}{}"sv,
-                            StringView(&str[last_printed_char_pos], match.global_offset - last_printed_char_pos),
+                            pre_match_length > 0 ? StringView(&str[last_printed_char_pos], pre_match_length) : ""sv,
                             match.view.to_string());
                         last_printed_char_pos = match.global_offset + match.view.length();
                     }
-                    outln("{}", StringView(&str[last_printed_char_pos], str.length() - last_printed_char_pos));
+                    auto remaining_length = str.length() - last_printed_char_pos;
+                    outln("{}", remaining_length > 0 ? StringView(&str[last_printed_char_pos], remaining_length) : ""sv);
                 }
 
                 return true;