patch "Revert "android: binder: Sanity check at binder ioctl"" added to char-misc-next

This is a note to let you know that I've just added the patch titled

Revert "android: binder: Sanity check at binder ioctl"

to my char-misc git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-next branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will also be merged in the next major kernel release during the merge window.

If you have any questions about this process, please let me know.

From: Todd Kjos <[email protected]>
Date: Wed, 5 Jul 2017 13:46:01 -0700
Subject: Revert "android: binder: Sanity check at binder ioctl"

This reverts commit a906d6931f3ccaf7de805643190765ddd7378e27.

The patch introduced a race in the binder driver. An attempt to fix the race was submitted in "[PATCH v2] android: binder: fix dangling pointer comparison", however the conclusion in the discussion for that patch was that the original patch should be reverted.

The reversion is being done as part of the fine-grained locking patchset since the patch would need to be refactored when proc->vmm_vm_mm is removed from struct binder_proc and added in the binder allocator.

---
 drivers/android/binder.c | 5 -----
 1 file changed, 5 deletions(-)

index aae4d8d4be36..157bd3e49ff4 100644
@@ -3247,10 +3247,6 @@ static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	/*pr_info("binder_ioctl: %d:%d %x %lx\n",
 			proc->pid, current->pid, cmd, arg);*/
 
-	if (unlikely(current->mm != proc->vma_vm_mm)) {
-		pr_err("current mm mismatch proc mm\n");
-		return -EINVAL;
-	}
 	trace_binder_ioctl(cmd, arg);
 
 	ret = wait_event_interruptible(binder_user_error_wait, binder_stop_on_user_error < 2);

@@ -3466,7 +3462,6 @@ static int binder_open(struct inode *nodp, struct file *filp)
 		return -ENOMEM;
 	get_task_struct(current);
 	proc->tsk = current;
-	proc->vma_vm_mm = current->mm;
 	INIT_LIST_HEAD(&proc->todo);
 	init_waitqueue_head(&proc->wait);
 	proc->default_priority = task_nice(current);

2.13.3