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authorRiley Andrews <riandrews@android.com>2016-02-10 08:05:33 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-02-12 07:06:46 +0300
commit83050a4e21979fe1821916fce2fca36255569ed3 (patch)
tree12535881c698ecdaef2085f530668de0cd96db25 /drivers/android
parent212265e5ad726ed7fd2ec7d61d36d9e0b0d3e655 (diff)
downloadlinux-83050a4e21979fe1821916fce2fca36255569ed3.tar.xz
android: drivers: Avoid 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. Cc: Colin Cross <ccross@android.com> Cc: Arve Hjønnevåg <arve@android.com> Cc: Dmitry Shmidt <dimitrysh@google.com> Cc: Rom Lemarchand <romlem@google.com> Cc: Serban Constantinescu <serban.constantinescu@arm.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Android Kernel Team <kernel-team@android.com> Signed-off-by: Dmitry Shmidt <dimitrysh@google.com> [jstultz: Minor commit message tweaks] Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/android')
-rw-r--r--drivers/android/binder.c15
1 files changed, 13 insertions, 2 deletions
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;