Re: [PATCH] fuzz: fix broken qtest check at rcu_disable_atfork
On 18/06/2020 18.05, Alexander Bulekov wrote: The qtest_enabled check introduced in d6919e4 always returns false, as it is called prior to configure_accelerators(). Instead of trying to skip rcu_disable_atfork in qemu_main, simply call rcu_enable_atfork in the fuzzer, after qemu_main returns. Reported-by: Thomas Huth Signed-off-by: Alexander Bulekov --- softmmu/vl.c| 12 +--- tests/qtest/fuzz/fuzz.c | 3 +++ 2 files changed, 4 insertions(+), 11 deletions(-) Thanks, queued to qtest-next now: https://gitlab.com/huth/qemu/-/commits/qtest-next/ Thomas
Re: [PATCH] fuzz: fix broken qtest check at rcu_disable_atfork
Patchew URL: https://patchew.org/QEMU/20200618160516.2817-1-alx...@bu.edu/ Hi, This series failed the asan build test. Please find the testing commands and their output below. If you have Docker installed, you can probably reproduce it locally. === TEST SCRIPT BEGIN === #!/bin/bash export ARCH=x86_64 make docker-image-fedora V=1 NETWORK=1 time make docker-test-debug@fedora TARGET_LIST=x86_64-softmmu J=14 NETWORK=1 === TEST SCRIPT END === CC qga/main.o CC qga/commands-posix.o CC qga/channel-posix.o /usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) CC qga/qapi-generated/qga-qapi-types.o CC qga/qapi-generated/qga-qapi-visit.o CC qga/qapi-generated/qga-qapi-commands.o --- GEN docs/interop/qemu-ga-ref.html GEN docs/interop/qemu-ga-ref.txt GEN docs/interop/qemu-ga-ref.7 /usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) LINKqemu-keymap LINKivshmem-client LINKivshmem-server /usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) LINKqemu-nbd /usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) /usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) LINKqemu-storage-daemon /usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) /usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) AS pc-bios/optionrom/multiboot.o AS pc-bios/optionrom/linuxboot.o CC pc-bios/optionrom/linuxboot_dma.o AS pc-bios/optionrom/kvmvapic.o LINKqemu-img AS pc-bios/optionrom/pvh.o /usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) CC pc-bios/optionrom/pvh_main.o BUILD pc-bios/optionrom/multiboot.img BUILD pc-bios/optionrom/linuxboot.img --- LINKqemu-edid SIGNpc-bios/optionrom/linuxboot_dma.bin LINKfsdev/virtfs-proxy-helper /usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) /usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) SIGNpc-bios/optionrom/kvmvapic.bin SIGNpc-bios/optionrom/pvh.bin LINKscsi/qemu-pr-helper LINKqemu-bridge-helper /usr/bin/ld/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) : /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) LINKvirtiofsd /usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from
[PATCH] fuzz: fix broken qtest check at rcu_disable_atfork
The qtest_enabled check introduced in d6919e4 always returns false, as
it is called prior to configure_accelerators(). Instead of trying to
skip rcu_disable_atfork in qemu_main, simply call rcu_enable_atfork in
the fuzzer, after qemu_main returns.
Reported-by: Thomas Huth
Signed-off-by: Alexander Bulekov
---
softmmu/vl.c| 12 +---
tests/qtest/fuzz/fuzz.c | 3 +++
2 files changed, 4 insertions(+), 11 deletions(-)
diff --git a/softmmu/vl.c b/softmmu/vl.c
index f669c06ede..95e2fed7f4 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -3832,17 +3832,7 @@ void qemu_init(int argc, char **argv, char **envp)
machine_class);
os_daemonize();
-
-/*
- * If QTest is enabled, keep the rcu_atfork enabled, since system processes
- * may be forked testing purposes (e.g. fork-server based fuzzing) The fork
- * should happen before a signle cpu instruction is executed, to prevent
- * deadlocks. See commit 73c6e40, rcu: "completely disable pthread_atfork
- * callbacks as soon as possible"
- */
-if (!qtest_enabled()) {
-rcu_disable_atfork();
-}
+rcu_disable_atfork();
if (pid_file && !qemu_write_pidfile(pid_file, )) {
error_reportf_err(err, "cannot create PID file: ");
diff --git a/tests/qtest/fuzz/fuzz.c b/tests/qtest/fuzz/fuzz.c
index a44fe479db..a36d9038e0 100644
--- a/tests/qtest/fuzz/fuzz.c
+++ b/tests/qtest/fuzz/fuzz.c
@@ -211,5 +211,8 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char
***envp)
qemu_init(result.we_wordc, result.we_wordv, NULL);
+/* re-enable the rcu atfork, which was previously disabled in qemu_init */
+rcu_enable_atfork();
+
return 0;
}
--
2.26.2
