8382fcac "pidns: Outlaw thread creation after unshare(CLONE_NEWPID)"
nacks CLONE_VM if the forking process unshared pid_ns, this obviously
breaks vfork:
int main(void)
{
assert(unshare(CLONE_NEWUSER | CLONE_NEWPID) == 0);
assert(vfork() >= 0);
_exit(0);
return 0;
}
fails without this patch.
Change this check to use CLONE_SIGHAND instead. This also forbids
CLONE_THREAD automatically, and this is what the comment implies.
We could probably even drop CLONE_SIGHAND and use CLONE_THREAD,
but it would be safer to not do this. The current check denies
CLONE_SIGHAND implicitely and there is no reason to change this.
Reported-by: Colin Walters <walt...@redhat.com>
Signed-off-by: Oleg Nesterov <o...@redhat.com>
---
kernel/fork.c | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/fork.c b/kernel/fork.c
index e23bb19..86f5376 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1173,10 +1173,10 @@ static struct task_struct *copy_process(unsigned long
clone_flags,
return ERR_PTR(-EINVAL);
/*
- * If the new process will be in a different pid namespace
- * don't allow the creation of threads.
+ * If the new process will be in a different pid namespace don't
+ * allow the creation of threads, or share the signal handlers.
*/
- if ((clone_flags & (CLONE_VM|CLONE_NEWPID)) &&
+ if ((clone_flags & (CLONE_SIGHAND | CLONE_NEWPID)) &&
(task_active_pid_ns(current) != current->nsproxy->pid_ns))
return ERR_PTR(-EINVAL);
--
1.5.5.1
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