* [committed] libstdc++: Fix past-the-end increment in std::format [PR110862]
@ 2023-08-07 21:12 Jonathan Wakely
0 siblings, 0 replies; only message in thread
From: Jonathan Wakely @ 2023-08-07 21:12 UTC (permalink / raw)
To: libstdc++, gcc-patches
Tested x86_64-linux. Pushed to trunk. gcc-13 backport to follow.
-- >8 --
At the end of a replacement field we should check that the closing brace
is actually present before incrementing past it.
libstdc++-v3/ChangeLog:
PR libstdc++/110862
* include/std/format (_Scanner::_M_on_replacement_field):
Check for expected '}' before incrementing iterator.
* testsuite/std/format/string.cc: Check "{0:{0}" format string.
---
libstdc++-v3/include/std/format | 4 +++-
libstdc++-v3/testsuite/std/format/string.cc | 13 +++++++++++++
2 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format
index 1e0ef612ddd..0debbae5ba8 100644
--- a/libstdc++-v3/include/std/format
+++ b/libstdc++-v3/include/std/format
@@ -3534,7 +3534,9 @@ namespace __format
_M_pc.advance_to(__ptr);
}
_M_format_arg(__id);
- _M_pc.advance_to(_M_pc.begin() + 1); // Move past '}'
+ if (begin() == end() || *begin() != '}')
+ __format::__unmatched_left_brace_in_format_string();
+ _M_pc.advance_to(begin() + 1); // Move past '}'
}
constexpr virtual void _M_format_arg(size_t __id) = 0;
diff --git a/libstdc++-v3/testsuite/std/format/string.cc b/libstdc++-v3/testsuite/std/format/string.cc
index d28135ec260..6a45237b8c4 100644
--- a/libstdc++-v3/testsuite/std/format/string.cc
+++ b/libstdc++-v3/testsuite/std/format/string.cc
@@ -128,6 +128,19 @@ test_format_spec()
VERIFY( ! is_format_string_for("{:9999999}", 1) );
}
+void
+test_pr110862()
+{
+ try {
+ // PR libstdc++/110862 out-of-bounds read on invalid format string
+ (void) std::vformat("{0:{0}", std::make_format_args(1));
+ VERIFY( false );
+ } catch (const std::format_error& e) {
+ std::string_view what = e.what();
+ VERIFY( what.find("unmatched left brace") != what.npos );
+ }
+}
+
int main()
{
test_no_args();
--
2.41.0
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2023-08-07 21:12 [committed] libstdc++: Fix past-the-end increment in std::format [PR110862] Jonathan Wakely
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