| Message ID | 20240304144456.3825935-2-berrange@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | Fix CI build on Free BSD 13 | expand |
On Mon, 4 Mar 2024 at 14:46, Daniel P. Berrangé <berrange@redhat.com> wrote: > > Clang 17 will segv if given -fzero-call-used-regs and optimization > is enabled. Since upstream hasn't triaged the bug, distros are > increasingly shipping with broken Clang. > > https://github.com/llvm/llvm-project/issues/75168 > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=277474 > Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> > --- > meson.build | 17 ++++++++++++----- > 1 file changed, 12 insertions(+), 5 deletions(-) > > diff --git a/meson.build b/meson.build > index 0ef1654e86..762798f2ee 100644 > --- a/meson.build > +++ b/meson.build > @@ -555,17 +555,24 @@ endif > # Check further flags that make QEMU more robust against malicious parties > > hardening_flags = [ > - # Zero out registers used during a function call > - # upon its return. This makes it harder to assemble > - # ROP gadgets into something usable > - '-fzero-call-used-regs=used-gpr', > - > # Initialize all stack variables to zero. This makes > # it harder to take advantage of uninitialized stack > # data to drive exploits > '-ftrivial-auto-var-init=zero', > ] > > +# Zero out registers used during a function call > +# upon its return. This makes it harder to assemble > +# ROP gadgets into something usable > +# > +# NB: CLang 17 is broken and SEGVs "Clang" > +# https://github.com/llvm/llvm-project/issues/75168 > +if cc.compiles('extern struct { void (*cb)(void); } s; void f(void) { s.cb(); }', > + name: '-fzero-call-used-regs=used-gpr', > + args: ['-O2', '-fzero-call-used-regs=used-gpr']) > + hardening_flags += '-fzero-call-used-regs=used-gpr' > +endif > + > qemu_common_flags += cc.get_supported_arguments(hardening_flags) > > add_global_arguments(qemu_common_flags, native: false, language: all_languages) Reviewed-by: Peter Maydell <peter.maydell@linaro.org> The stable releases don't have the use of -fzero-call-used-regs, so we don't need to backport this. thanks -- PMM
diff --git a/meson.build b/meson.build index 0ef1654e86..762798f2ee 100644 --- a/meson.build +++ b/meson.build @@ -555,17 +555,24 @@ endif # Check further flags that make QEMU more robust against malicious parties hardening_flags = [ - # Zero out registers used during a function call - # upon its return. This makes it harder to assemble - # ROP gadgets into something usable - '-fzero-call-used-regs=used-gpr', - # Initialize all stack variables to zero. This makes # it harder to take advantage of uninitialized stack # data to drive exploits '-ftrivial-auto-var-init=zero', ] +# Zero out registers used during a function call +# upon its return. This makes it harder to assemble +# ROP gadgets into something usable +# +# NB: CLang 17 is broken and SEGVs +# https://github.com/llvm/llvm-project/issues/75168 +if cc.compiles('extern struct { void (*cb)(void); } s; void f(void) { s.cb(); }', + name: '-fzero-call-used-regs=used-gpr', + args: ['-O2', '-fzero-call-used-regs=used-gpr']) + hardening_flags += '-fzero-call-used-regs=used-gpr' +endif + qemu_common_flags += cc.get_supported_arguments(hardening_flags) add_global_arguments(qemu_common_flags, native: false, language: all_languages)
Clang 17 will segv if given -fzero-call-used-regs and optimization is enabled. Since upstream hasn't triaged the bug, distros are increasingly shipping with broken Clang. https://github.com/llvm/llvm-project/issues/75168 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=277474 Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> --- meson.build | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-)