From: Tom Hughes <tom@compton.nu>
Date: Thu, 20 Feb 2020 09:14:24 +0000 (+0000)
Subject: Allow clone with CLONE_VFORK and no CLONE_VM
X-Git-Tag: VALGRIND_3_16_0~99
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3e11902ce28ff43cff679bf2453c597d568fde8f;p=thirdparty%2Fvalgrind.git

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 --git a/NEWS b/NEWS
index 99ece46f62..07dd91489f 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 bc09628fd0..a4c106f684 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).