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

PATCH New Todd Kjos 1 participant 1 message Jul 5, 2017 Android drivers

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Todd Kjos

author maintainer

2017-07-05 20:46 UTC #0 lore raw

PATCH v2 1/37 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.

Also needs reversion in 4.9 LTS

Signed-off-by Todd Kjos <[email protected]>

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

drivers/android/binder.c +0 -5

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);

Signature · 1 line

2.13.2.725.g09c95d1e9-goog