Fix bug found by fuzzing

fmtlib · Jan 13, 2023 · 5dc570c · 5dc570c
1 parent 6a0f6ff
commit 5dc570c
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Showing 2 changed files with 8 additions and 0 deletions.
diff --git a/include/fmt/chrono.h b/include/fmt/chrono.h
@@ -706,6 +706,7 @@ FMT_CONSTEXPR const Char* parse_chrono_format(const Char* begin,
     }
     if (begin != ptr) handler.on_text(begin, ptr);
     c = *++ptr;  // consume '%'
+    if (ptr == end) FMT_THROW(format_error("invalid format"));
     switch (c) {
     case '_':
       pad = pad_type::space;

diff --git a/test/chrono-test.cc b/test/chrono-test.cc
@@ -921,6 +921,13 @@ TEST(chrono_test, timestamps_sub_seconds) {
 }
 
 TEST(chrono_test, glibc_extensions) {
+  EXPECT_THROW_MSG((void)fmt::format(runtime("{:%0}"), std::chrono::seconds()),
+                   fmt::format_error, "invalid format");
+  EXPECT_THROW_MSG((void)fmt::format(runtime("{:%_}"), std::chrono::seconds()),
+                   fmt::format_error, "invalid format");
+  EXPECT_THROW_MSG((void)fmt::format(runtime("{:%-}"), std::chrono::seconds()),
+                   fmt::format_error, "invalid format");
+
   {
     const auto d = std::chrono::hours(1) + std::chrono::minutes(2) +
                    std::chrono::seconds(3);