MDEV-20377: Make WITH_MSAN more usable

MemorySanitizer (clang -fsanitize=memory) requires that all code
be compiled with instrumentation enabled. The only exception is the
C runtime library. Failure to use instrumented libraries will cause
bogus messages about memory being uninitialized.

In WITH_MSAN builds, we must avoid calling getservbyname(),
because even though it is a standard library function, it is
not instrumented, not even in clang 10.

Note: Before MariaDB Server 10.5, ./mtr will typically fail
due to the old PCRE library, which was updated in MDEV-14024.

The following cmake options were tested on 10.5
in commit 94d0bb4dbeb28a94d1f87fdd55f4297ff3df0157:

cmake \
-DCMAKE_C_FLAGS='-march=native -O2' \
-DCMAKE_CXX_FLAGS='-stdlib=libc++ -march=native -O2' \
-DWITH_EMBEDDED_SERVER=OFF -DWITH_UNIT_TESTS=OFF -DCMAKE_BUILD_TYPE=Debug \
-DWITH_INNODB_{BZIP2,LZ4,LZMA,LZO,SNAPPY}=OFF \
-DPLUGIN_{ARCHIVE,TOKUDB,MROONGA,OQGRAPH,ROCKSDB,CONNECT,SPIDER}=NO \
-DWITH_SAFEMALLOC=OFF \
-DWITH_{ZLIB,SSL,PCRE}=bundled \
-DHAVE_LIBAIO_H=0 \
-DWITH_MSAN=ON

MEM_MAKE_DEFINED(): An alias for VALGRIND_MAKE_MEM_DEFINED()
and __msan_unpoison().

MEM_GET_VBITS(), MEM_SET_VBITS(): Aliases for
VALGRIND_GET_VBITS(), VALGRIND_SET_VBITS(), __msan_copy_shadow().

InnoDB: Replace the UNIV_MEM_ macros with corresponding MEM_ macros.

ut_crc32_8_hw(), ut_crc32_64_low_hw(): Use the compiler built-in
functions instead of inline assembler when building WITH_MSAN.
This will require at least -msse4.2 when building for IA-32 or AMD64.
The inline assembler would not be instrumented, and would thus cause
bogus failures.

1 files changed, 2 insertions, 0 deletions

diff --git a/sql/mysqld.cc b/sql/mysqld.cc
index e40d5c38233..afe969b6e8d 100644
--- a/sql/mysqld.cc
+++ b/sql/mysqld.cc
@@ -2415,9 +2415,11 @@ static void set_ports()
     */
 
 #if MYSQL_PORT_DEFAULT == 0
+# if !__has_feature(memory_sanitizer) // Work around MSAN deficiency
     struct  servent *serv_ptr;
     if ((serv_ptr= getservbyname("mysql", "tcp")))
       SYSVAR_AUTOSIZE(mysqld_port, ntohs((u_short) serv_ptr->s_port));
+# endif
 #endif
     if ((env = getenv("MYSQL_TCP_PORT")))
     {