The vector<bool>::shrink_to_fit() implementation will allocate new
storage even if the vector is empty. That then leads to the
end-of-storage pointer being non-null and equal to the _M_start._M_p
pointer, which means that _M_end_addr() has undefined behaviour.
The fix is to stop doing a useless zero-sized allocation in
shrink_to_fit(), so that _M_start._M_p and _M_end_of_storage are both
null after an empty vector shrinks.
Signed-off-by: Jonathan Wakely <jwak...@redhat.com>
libstdc++-v3/ChangeLog:
PR libstdc++/100153
* include/bits/vector.tcc (vector<bool>::_M_shrink_to_fit()):
When size() is zero just deallocate and reset.
Tested powerpc64le-linux. Committed to trunk.
commit 681707ec28d56494fa61a80c62500724d55f8586
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Tue Apr 20 16:16:13 2021
libstdc++: Do not allocate a zero-size vector<bool> [PR 100153]
The vector<bool>::shrink_to_fit() implementation will allocate new
storage even if the vector is empty. That then leads to the
end-of-storage pointer being non-null and equal to the _M_start._M_p
pointer, which means that _M_end_addr() has undefined behaviour.
The fix is to stop doing a useless zero-sized allocation in
shrink_to_fit(), so that _M_start._M_p and _M_end_of_storage are both
null after an empty vector shrinks.
Signed-off-by: Jonathan Wakely <jwak...@redhat.com>
libstdc++-v3/ChangeLog:
PR libstdc++/100153
* include/bits/vector.tcc (vector<bool>::_M_shrink_to_fit()):
When size() is zero just deallocate and reset.
diff --git a/libstdc++-v3/include/bits/vector.tcc
b/libstdc++-v3/include/bits/vector.tcc
index caee5cbfc2f..16366e03c86 100644
--- a/libstdc++-v3/include/bits/vector.tcc
+++ b/libstdc++-v3/include/bits/vector.tcc
@@ -944,7 +944,13 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
return false;
__try
{
- _M_reallocate(size());
+ if (size_type __n = size())
+ _M_reallocate(__n);
+ else
+ {
+ this->_M_deallocate();
+ this->_M_impl._M_reset();
+ }
return true;
}
__catch(...)
