From aa29c32d396b6e7cf9192e607760fa1d6a56cc21 Mon Sep 17 00:00:00 2001 From: Riley Andrews Date: Mon, 9 Nov 2015 13:16:32 -0800 Subject: android: drivers: workaround debugfs race in binder If a /d/binder/proc/[pid] entry is kept open after linux has torn down the associated process, binder_proc_show can deference an invalid binder_proc that has been stashed in the debugfs inode. Validate that the binder_proc ptr passed into binder_proc_show has not been freed by looking for it within the global process list whilst the global lock is held. If the ptr is not valid, print nothing. Bug: 19587483 Change-Id: Idd5ad79f5648b7eed49d1ec75ae93f9e12a74ee9 Signed-off-by: Dmitry Shmidt --- drivers/android/binder.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) (limited to 'drivers/android/binder.c') diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 1db376184955..f0ce9959d14d 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -3600,13 +3600,24 @@ static int binder_transactions_show(struct seq_file *m, void *unused) static int binder_proc_show(struct seq_file *m, void *unused) { + struct binder_proc *itr; struct binder_proc *proc = m->private; int do_lock = !binder_debug_no_lock; + bool valid_proc = false; if (do_lock) binder_lock(__func__); - seq_puts(m, "binder proc state:\n"); - print_binder_proc(m, proc, 1); + + hlist_for_each_entry(itr, &binder_procs, proc_node) { + if (itr == proc) { + valid_proc = true; + break; + } + } + if (valid_proc) { + seq_puts(m, "binder proc state:\n"); + print_binder_proc(m, proc, 1); + } if (do_lock) binder_unlock(__func__); return 0; -- cgit v1.2.3