From: "Dmitry V. Levin" <ldv@altlinux.org>
To: Christian Brauner <christian@brauner.io>
Cc: Anatoly Pugachev <matorola@gmail.com>, linux-kernel@vger.kernel.org
Subject: [PATCH v2] clone: fix CLONE_PIDFD support
Date: Sun, 14 Jul 2019 19:20:47 +0300 [thread overview]
Message-ID: <20190714162047.GB10389@altlinux.org> (raw)
In-Reply-To: <20190714161449.GA10389@altlinux.org>
The introduction of clone3 syscall accidentally broke CLONE_PIDFD
support in traditional clone syscall on compat x86 and those
architectures that use do_fork to implement clone syscall.
This bug was found by strace test suite.
Link: https://strace.io/logs/strace/2019-07-12
Fixes: 7f192e3cd316 ("fork: add clone3")
Bisected-and-tested-by: Anatoly Pugachev <matorola@gmail.com>
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
---
arch/x86/ia32/sys_ia32.c | 4 ++++
include/linux/sched/task.h | 1 +
kernel/fork.c | 17 +++++++++++++++--
3 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/arch/x86/ia32/sys_ia32.c b/arch/x86/ia32/sys_ia32.c
index 64a6c952091e..21790307121e 100644
--- a/arch/x86/ia32/sys_ia32.c
+++ b/arch/x86/ia32/sys_ia32.c
@@ -239,6 +239,7 @@ COMPAT_SYSCALL_DEFINE5(x86_clone, unsigned long, clone_flags,
{
struct kernel_clone_args args = {
.flags = (clone_flags & ~CSIGNAL),
+ .pidfd = parent_tidptr,
.child_tid = child_tidptr,
.parent_tid = parent_tidptr,
.exit_signal = (clone_flags & CSIGNAL),
@@ -246,5 +247,8 @@ COMPAT_SYSCALL_DEFINE5(x86_clone, unsigned long, clone_flags,
.tls = tls_val,
};
+ if (!legacy_clone_args_valid(&args))
+ return -EINVAL;
+
return _do_fork(&args);
}
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 109a0df5af39..0497091e40c1 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -89,6 +89,7 @@ extern void exit_files(struct task_struct *);
extern void exit_itimers(struct signal_struct *);
extern long _do_fork(struct kernel_clone_args *kargs);
+extern bool legacy_clone_args_valid(const struct kernel_clone_args *kargs);
extern long do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *);
struct task_struct *fork_idle(int);
struct mm_struct *copy_init_mm(void);
diff --git a/kernel/fork.c b/kernel/fork.c
index 8f3e2d97d771..ef1e05a68827 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2406,6 +2406,16 @@ long _do_fork(struct kernel_clone_args *args)
return nr;
}
+bool legacy_clone_args_valid(const struct kernel_clone_args *kargs)
+{
+ /* clone(CLONE_PIDFD) uses parent_tidptr to return a pidfd */
+ if ((kargs->flags & CLONE_PIDFD) &&
+ (kargs->flags & CLONE_PARENT_SETTID))
+ return false;
+
+ return true;
+}
+
#ifndef CONFIG_HAVE_COPY_THREAD_TLS
/* For compatibility with architectures that call do_fork directly rather than
* using the syscall entry points below. */
@@ -2417,6 +2427,7 @@ long do_fork(unsigned long clone_flags,
{
struct kernel_clone_args args = {
.flags = (clone_flags & ~CSIGNAL),
+ .pidfd = parent_tidptr,
.child_tid = child_tidptr,
.parent_tid = parent_tidptr,
.exit_signal = (clone_flags & CSIGNAL),
@@ -2424,6 +2435,9 @@ long do_fork(unsigned long clone_flags,
.stack_size = stack_size,
};
+ if (!legacy_clone_args_valid(&args))
+ return -EINVAL;
+
return _do_fork(&args);
}
#endif
@@ -2505,8 +2519,7 @@ SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
.tls = tls,
};
- /* clone(CLONE_PIDFD) uses parent_tidptr to return a pidfd */
- if ((clone_flags & CLONE_PIDFD) && (clone_flags & CLONE_PARENT_SETTID))
+ if (!legacy_clone_args_valid(&args))
return -EINVAL;
return _do_fork(&args);
--
ldv
next prev parent reply other threads:[~2019-07-14 16:20 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-14 12:02 [PATCH] clone: fix CLONE_PIDFD support Dmitry V. Levin
2019-07-14 12:17 ` Christian Brauner
2019-07-14 14:10 ` Dmitry V. Levin
2019-07-14 14:23 ` Christian Brauner
2019-07-14 16:14 ` Dmitry V. Levin
2019-07-14 16:20 ` Dmitry V. Levin [this message]
2019-07-14 18:21 ` [PATCH v2] " Christian Brauner
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