diff options
| author | Todd Kjos <tkjos@android.com> | 2019-06-12 13:29:27 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-06-13 10:35:55 +0200 |
| commit | a370003cc301d4361bae20c9ef615f89bf8d1e8a (patch) | |
| tree | d96c2242a45c688ac249891b7a4d39851a2b2e19 | |
| parent | b7108486d2d60357dec274276e2f69128f29dcdc (diff) | |
| download | linux-a370003cc301d4361bae20c9ef615f89bf8d1e8a.tar.gz linux-a370003cc301d4361bae20c9ef615f89bf8d1e8a.tar.bz2 linux-a370003cc301d4361bae20c9ef615f89bf8d1e8a.zip | |
binder: fix possible UAF when freeing buffer
There is a race between the binder driver cleaning
up a completed transaction via binder_free_transaction()
and a user calling binder_ioctl(BC_FREE_BUFFER) to
release a buffer. It doesn't matter which is first but
they need to be protected against running concurrently
which can result in a UAF.
Signed-off-by: Todd Kjos <tkjos@google.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/android/binder.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 748ac489ef7e..bc26b5511f0a 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -1941,8 +1941,18 @@ static void binder_free_txn_fixups(struct binder_transaction *t) static void binder_free_transaction(struct binder_transaction *t) { - if (t->buffer) - t->buffer->transaction = NULL; + struct binder_proc *target_proc = t->to_proc; + + if (target_proc) { + binder_inner_proc_lock(target_proc); + if (t->buffer) + t->buffer->transaction = NULL; + binder_inner_proc_unlock(target_proc); + } + /* + * If the transaction has no target_proc, then + * t->buffer->transaction has already been cleared. + */ binder_free_txn_fixups(t); kfree(t); binder_stats_deleted(BINDER_STAT_TRANSACTION); @@ -3551,10 +3561,12 @@ err_invalid_target_handle: static void binder_free_buf(struct binder_proc *proc, struct binder_buffer *buffer) { + binder_inner_proc_lock(proc); if (buffer->transaction) { buffer->transaction->buffer = NULL; buffer->transaction = NULL; } + binder_inner_proc_unlock(proc); if (buffer->async_transaction && buffer->target_node) { struct binder_node *buf_node; struct binder_work *w; |