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* [gcc(refs/users/marxin/heads/marxin-gcc-benchmark-branch)] libstdc++: Fix incorrect size calculation in PMR resource (PR 94906)
@ 2020-05-27 11:17 Martin Liska
0 siblings, 0 replies; only message in thread
From: Martin Liska @ 2020-05-27 11:17 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:bb27781b64162e1769df15e0c97e8d2145d2d10d
commit bb27781b64162e1769df15e0c97e8d2145d2d10d
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Mon May 4 21:13:28 2020 +0100
libstdc++: Fix incorrect size calculation in PMR resource (PR 94906)
Calculating the size of a chunk being returned to the upstream allocator
was done with a 32-bit type, so it wrapped if the chunk was 4GB or
larger.
I don't know how to test this without allocating 4GB, so there's no test
in the testsuite. It has been tested manually with allocations sizes and
alignments exceeding 4GB.
PR libstdc++/94906
* src/c++17/memory_resource.cc
(monotonic_buffer_resource::_Chunk::release): Use size_t for shift
operands.
Diff:
---
libstdc++-v3/ChangeLog | 7 +++++++
libstdc++-v3/src/c++17/memory_resource.cc | 4 ++--
2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 739ab9eeb29..9cc811c884f 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,10 @@
+2020-05-04 Jonathan Wakely <jwakely@redhat.com>
+
+ PR libstdc++/94906
+ * src/c++17/memory_resource.cc
+ (monotonic_buffer_resource::_Chunk::release): Use size_t for shift
+ operands.
+
2020-05-04 Nathan Sidwell <nathan@acm.org>
PR libstdc++/94747
diff --git a/libstdc++-v3/src/c++17/memory_resource.cc b/libstdc++-v3/src/c++17/memory_resource.cc
index 1acab19e306..95352b23537 100644
--- a/libstdc++-v3/src/c++17/memory_resource.cc
+++ b/libstdc++-v3/src/c++17/memory_resource.cc
@@ -228,8 +228,8 @@ namespace pmr
if (__ch->_M_canary != (__ch->_M_size | __ch->_M_align))
return; // buffer overflow detected!
- size_t __size = (1u << __ch->_M_size);
- size_t __align = (1u << __ch->_M_align);
+ size_t __size = (size_t)1 << __ch->_M_size;
+ size_t __align = (size_t)1 << __ch->_M_align;
void* __start = (char*)(__ch + 1) - __size;
__r->deallocate(__start, __size, __align);
}
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