Re: [Libguestfs] [PATCH nbdkit 2/3] configure: Add --disable-linker-script flag

This flag allows you to disable the linker script (for the server only). This is necessary for ASAN to work as explained in the documentation. Thanks Eric Blake for helping me with working out the root cause. --- configure.ac | 30 ++++++++++++++++++++++++------ server/Makefile.am | 5 ----- README | 13 +++++++++++++ 3 files changed, 37 insertions(+), 11 deletions(-) diff --git a/configure.ac b/configure.ac index f86215d9..404d4e23 100644 --- a/configure.ac +++ b/configure.ac @@ -502,17 +502,19 @@ main (int argc, char *argv[]) ]) AM_CONDITIONAL([HAVE_ICONV], [test "x$iconv_working" = "xyes"]) +use_linker_script_for_server=yes + dnl Don't use linker script for the server on FreeBSD because dnl FreeBSD's linker is broken. See eg: dnl https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=190851 -AC_MSG_CHECKING([if we should use a linker script for the server]) +AC_MSG_CHECKING([if we should disable the linker script (FreeBSD only)]) AS_CASE([$host_os], - [freebsd*], [use_linker_script_for_server=no], - [use_linker_script_for_server=yes] + [freebsd*], [ + use_linker_script_for_server=no + AC_MSG_RESULT([yes]) + ], + [AC_MSG_RESULT([no])] ) -AC_MSG_RESULT([$use_linker_script_for_server]) -AM_CONDITIONAL([USE_LINKER_SCRIPT_FOR_SERVER], - [test "x$use_linker_script_for_server" = "xyes"]) dnl Check if -rdynamic linker flag works. acx_nbdkit_save_LDFLAGS="${LDFLAGS}"

@@ -691,9 +693,23 @@ AC_ARG_ENABLE([libfuzzer], [enable_libfuzzer=no]) AS_IF([test "x$enable_libfuzzer" = "xyes"],[ AC_DEFINE([ENABLE_LIBFUZZER],[1],[Enable special libFuzzer binary]) + # We have to disable the linker script for libFuzzer because Clang + # adds loads of fuzzer and ASAN-related symbols that are required + # by the plugins but which our linker script tries to hide. + use_linker_script_for_server=no ]) AM_CONDITIONAL([ENABLE_LIBFUZZER],[test "x$enable_libfuzzer" = "xyes"])

+dnl Should we use the linker script with the server? Note +dnl some tests above may set this variable. +AC_ARG_ENABLE([linker-script], + [AS_HELP_STRING([--disable-linker-script], + [disable linker script for server (developers only)])], + [use_linker_script_for_server=$enableval], + [])

+AM_CONDITIONAL([USE_LINKER_SCRIPT_FOR_SERVER], + [test "x$use_linker_script_for_server" = "xyes"]) + dnl Bash completion. PKG_CHECK_MODULES([BASH_COMPLETION], [bash-completion >= 2.0], [ bash_completion=yes

@@ -1419,6 +1435,8 @@ feature "bash-completion ........................ " \ test "x$HAVE_BASH_COMPLETION_TRUE" = "x" feature "libfuzzer .............................. " \ test "x$ENABLE_LIBFUZZER_TRUE" = "x" +feature "linker script .......................... " \ + test "x$USE_LINKER_SCRIPT_FOR_SERVER_TRUE" = "x" feature "manual pages ........................... " \ test "x$HAVE_POD_TRUE" = "x" feature "SELinux ................................ " \

diff --git a/server/Makefile.am b/server/Makefile.am index 0039d1da..9ab621d5 100644 --- a/server/Makefile.am +++ b/server/Makefile.am @@ -108,13 +108,8 @@ nbdkit_LDFLAGS = \ $(NULL) EXTRA_nbdkit_DEPENDENCIES = nbdkit.syms if USE_LINKER_SCRIPT_FOR_SERVER -# We have to disable the linker script for libFuzzer because Clang -# adds loads of fuzzer and ASAN-related symbols that are required by -# the plugins but which our linker script tries to hide. -if !ENABLE_LIBFUZZER nbdkit_LDFLAGS += -Wl,--version-script=$(srcdir)/nbdkit.syms endif -endif if IS_WINDOWS # On Windows, generate an import library so that plugins can link

diff --git a/README b/README index 3480d561..7aa93b1d 100644 --- a/README +++ b/README @@ -324,6 +324,19 @@ For further information, see: https://libguestfs.org/ https://github.com/NetworkBlockDevice/nbd/blob/master/doc/proto.md +Address sanitizer (ASAN) +------------------------ + +You can compile nbdkit with clang and ASAN with: + + ./configure CC=clang CXX=clang++ \ + CFLAGS="-O0 -g -fsanitize=address -fno-omit-frame-pointer" \ + --disable-linker-script \ + --disable-golang + make clean + make + ASAN_OPTIONS="allocator_may_return_null=1 detect_leaks=false" make check + Test coverage -------------