Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

ba0f4722 · Linus Torvalds <[email protected]> · 2020-01-18 12:29:13 -08:00

Pull rseq fixes from Ingo Molnar:
 "Two rseq bugfixes:

   - CLONE_VM !CLONE_THREAD didn't work properly, the kernel would end
     up corrupting the TLS of the parent. Technically a change in the
     ABI but the previous behavior couldn't resonably have been relied
     on by applications so this looks like a valid exception to the ABI
     rule.

   - Make the RSEQ_FLAG_UNREGISTER ABI behavior consistent with the
     handling of other flags. This is not thought to impact any
     applications either"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rseq: Unregister rseq for clone CLONE_VM
  rseq: Reject unknown flags on rseq unregister

Commit: ba0f47220384ff160c9df93dedbbef26d7b67f7b
Parents: 8cac8990 · 463f550f

Merge commit. Changes below are compared with the first parent: 8cac8990.

Changes

2 files changed · +4 −2

File	Status	Add	Del	Content
include/linux/sched.h	modified	+2	−2	View file
kernel/rseq.c	modified	+2	−0	View file

include/linux/sched.h

View file

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 467d260..716ad1d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1929,11 +1929,11 @@ static inline void rseq_migrate(struct task_struct *t)
 
 /*
  * If parent process has a registered restartable sequences area, the
- * child inherits. Only applies when forking a process, not a thread.
+ * child inherits. Unregister rseq for a clone with CLONE_VM set.
  */
 static inline void rseq_fork(struct task_struct *t, unsigned long clone_flags)
 {
-	if (clone_flags & CLONE_THREAD) {
+	if (clone_flags & CLONE_VM) {
 		t->rseq = NULL;
 		t->rseq_sig = 0;
 		t->rseq_event_mask = 0;

kernel/rseq.c

View file

diff --git a/kernel/rseq.c b/kernel/rseq.c
index 27c48eb..a4f86a9 100644
--- a/kernel/rseq.c
+++ b/kernel/rseq.c
@@ -310,6 +310,8 @@ SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len,
 	int ret;
 
 	if (flags & RSEQ_FLAG_UNREGISTER) {
+		if (flags & ~RSEQ_FLAG_UNREGISTER)
+			return -EINVAL;
 		/* Unregister rseq for current thread. */
 		if (current->rseq != rseq || !current->rseq)
 			return -EINVAL;