[Valgrind-developers] [valgrind] Allow clone with CLONE_VFORK and no CLONE_VM

[Tom H. <tom...@so...>]

https://sourceware.org/git/gitweb.cgi?p=valgrind.git;h=3e11902ce28ff43cff679bf2453c597d568fde8f

commit 3e11902ce28ff43cff679bf2453c597d568fde8f
Author: Tom Hughes <to...@co...>
Date:   Thu Feb 20 09:14:24 2020 +0000

    Allow clone with CLONE_VFORK and no CLONE_VM
    
    The CLONE_VFORK flag causes the parent to suspend until the child
    exits or execs so without the memory sharing CLONE_VM would give
    this is really closer to fork but we convert vfork to fork by
    removing CLONE_VM anyway so there is no reason not to allow this.
    
    Fixes BZ#417906

Diff:
---
 NEWS                                | 1 +
 coregrind/m_syswrap/syswrap-linux.c | 1 +
 2 files changed, 2 insertions(+)

diff --git a/NEWS b/NEWS
index 99ece46..07dd914 100644
--- a/NEWS
+++ b/NEWS
@@ -117,6 +117,7 @@ n-i-bz  sys_statx: don't complain if both |filename| and |buf| are NULL.
 n-i-bz  Fix non-glibc build of test suite with s390x_features
 416667  gcc10 ppc64le impossible constraint in 'asm' in test_isa.
 417452  s390_insn_store_emit: dst->tag for HRcVec128
+417906  clone with CLONE_VFORK and no CLONE_VM fails
 
 
 Release 3.15.0 (12 April 2019)
diff --git a/coregrind/m_syswrap/syswrap-linux.c b/coregrind/m_syswrap/syswrap-linux.c
index bc09628..a4c106f 100644
--- a/coregrind/m_syswrap/syswrap-linux.c
+++ b/coregrind/m_syswrap/syswrap-linux.c
@@ -915,6 +915,7 @@ PRE(sys_clone)
       break;
 
    case VKI_CLONE_VFORK | VKI_CLONE_VM: /* vfork */
+   case VKI_CLONE_VFORK: /* vfork without memory sharing */
       cloneflags &= ~VKI_CLONE_VM;
       // FALLTHROUGH - assume vfork (somewhat) == fork, see ML_(do_fork_clone).