MDEV-28836 fixup

On GNU/Linux, even though the C11 aligned_alloc() appeared in
GNU libc early on, some custom memory allocators did not
implement it until recently. For example, before
gperftools/gperftools@d406f22853
the free() in tcmalloc would fail to free memory that was
returned by aligned_alloc(), because the latter would map to the
built-in allocator of libc. The Linux specific memalign() has a
similar interface and is safer to use, because it has been
available for a longer time. For AddressSanitizer, we will use
aligned_alloc() so that the constraint on size can be enforced.

buf_tmp_reserve_compression_buf(): When HAVE_ALIGNED_ALLOC holds,
round up the size to be an integer multiple of the alignment.

pfs_malloc(): In the unit test stub, round up the size to be an
integer multiple of the alignment.

configure.cmake

@@ -324,7 +324,14 @@ ENDIF()
 CHECK_FUNCTION_EXISTS (accept4 HAVE_ACCEPT4)
 CHECK_FUNCTION_EXISTS (access HAVE_ACCESS)
 CHECK_FUNCTION_EXISTS (alarm HAVE_ALARM)
-CHECK_FUNCTION_EXISTS (aligned_alloc HAVE_ALIGNED_ALLOC)
+IF (CMAKE_SYSTEM_NAME MATCHES "Linux" AND NOT WITH_ASAN)
+  # When an old custom memory allocator library is used, aligned_alloc()
+  # could invoke the built-in allocator in libc, not matching
+  # the overriden free() in the custom memory allocator.
+  SET(HAVE_ALIGNED_ALLOC 0)
+ELSE()
+  CHECK_FUNCTION_EXISTS (aligned_alloc HAVE_ALIGNED_ALLOC)
+ENDIF()
 SET(HAVE_ALLOCA 1)
 CHECK_FUNCTION_EXISTS (backtrace HAVE_BACKTRACE)
 CHECK_FUNCTION_EXISTS (backtrace_symbols HAVE_BACKTRACE_SYMBOLS)

include/aligned.h

@@ -14,12 +14,19 @@
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1335  USA */
 
+#ifdef HAVE_ALIGNED_ALLOC
+#elif defined __linux__
+# include <malloc.h>
+#endif
+
 inline void *aligned_malloc(size_t size, size_t alignment)
 {
 #ifdef _WIN32
   return _aligned_malloc(size, alignment);
 #elif defined HAVE_ALIGNED_ALLOC
   return aligned_alloc(alignment, size);
+#elif defined __linux__
+  return memalign(alignment, size);
 #else
   void *result;
   if (posix_memalign(&result, alignment, size))

storage/innobase/buf/buf0flu.cc

@@ -576,9 +576,12 @@ static void buf_tmp_reserve_compression_buf(buf_tmp_buffer_t* slot)
   buffer be bigger than input buffer. Adjust the allocated size. */
   ulint size= srv_page_size;
 #ifdef HAVE_LZO
-  size+= LZO1X_1_15_MEM_COMPRESS;
+  size= size + LZO1X_1_15_MEM_COMPRESS;
 #elif defined HAVE_SNAPPY
   size= snappy_max_compressed_length(size);
+#endif
+#if defined HAVE_ALIGNED_ALLOC && (defined HAVE_LZO || defined HAVE_SNAPPY)
+  size= MY_ALIGN(size, srv_page_size);
 #endif
   slot->comp_buf= static_cast<byte*>(aligned_malloc(size, srv_page_size));
 }

storage/perfschema/unittest/stub_pfs_global.h

@@ -26,6 +26,7 @@
 #include <pfs_global.h>
 #include <string.h>
 #include "aligned.h"
+#include "assume_aligned.h"
 
 bool pfs_initialized= false;
 size_t pfs_allocated_memory_size= 0;
@@ -47,9 +48,10 @@ void *pfs_malloc(PFS_builtin_memory_class *klass, size_t size, myf)
   if (--stub_alloc_fails_after_count <= 0)
     return NULL;
 
+  size= MY_ALIGN(size, CPU_LEVEL1_DCACHE_LINESIZE);
   void *ptr= aligned_malloc(size, CPU_LEVEL1_DCACHE_LINESIZE);
   if (ptr != NULL)
-    memset(ptr, 0, size);
+    memset_aligned<CPU_LEVEL1_DCACHE_LINESIZE>(ptr, 0, size);
   return ptr;
 }