From 19e6befddcd4b9a412ea54c28d200a4453a55fcb Mon Sep 17 00:00:00 2001
From: implicitfield <114500360+implicitfield@users.noreply.github.com>
Date: Fri, 25 Nov 2022 16:30:45 +0200
Subject: [PATCH] FuzzTar+tar: Advance the stream before continuing

Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=53733
This bug was caused by a regression introduced in c88d8a2.
---
 Meta/Lagom/Fuzzers/FuzzTar.cpp | 8 ++++++--
 Userland/Utilities/tar.cpp     | 2 ++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/Meta/Lagom/Fuzzers/FuzzTar.cpp b/Meta/Lagom/Fuzzers/FuzzTar.cpp
index 5e76197eae7..82c54d9789f 100644
--- a/Meta/Lagom/Fuzzers/FuzzTar.cpp
+++ b/Meta/Lagom/Fuzzers/FuzzTar.cpp
@@ -19,8 +19,12 @@ extern "C" int LLVMFuzzerTestOneInput(uint8_t const* data, size_t size)
     while (!tar_stream.finished()) {
         auto const& header = tar_stream.header();
 
-        if (!header.content_is_like_extended_header())
-            continue;
+        if (!header.content_is_like_extended_header()) {
+            if (tar_stream.advance().is_error())
+                return 0;
+            else
+                continue;
+        }
 
         switch (header.type_flag()) {
         case Archive::TarFileType::GlobalExtendedHeader:
diff --git a/Userland/Utilities/tar.cpp b/Userland/Utilities/tar.cpp
index dca9a189471..48e65b0ccec 100644
--- a/Userland/Utilities/tar.cpp
+++ b/Userland/Utilities/tar.cpp
@@ -124,6 +124,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                     VERIFY_NOT_REACHED();
                 }
 
+                TRY(tar_stream.advance());
                 continue;
             }
 
@@ -141,6 +142,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                     long_name.append(reinterpret_cast<char*>(buffer.data()), bytes_read);
 
                 local_overrides.set("path", long_name.to_string());
+                TRY(tar_stream.advance());
                 continue;
             }
             default: