binder: fix potential UAF of target_{proc,thread}

Commit 9474be34a727 ("binder: add failed transaction logging info")
dereferences target_{proc,thread} after they have been potentially
freed by binder_proc_dec_tmpref() and binder_thread_dec_tmpref().

This patch delays the release of the two references after their last
usage. Fixes the following two errors reported by smatch:

  drivers/android/binder.c:3562 binder_transaction() error: dereferencing freed memory 'target_proc'
  drivers/android/binder.c:3563 binder_transaction() error: dereferencing freed memory 'target_thread'

Fixes: 9474be34a727 ("binder: add failed transaction logging info")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Todd Kjos <tkjos@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20220517185817.598872-1-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 176bb046368057f679a4e7e974edb4aa71c0744e..9e36608eac6cc9276486c1f12c8af6dd8e6ab5e2 100644 (file)
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -3546,10 +3546,6 @@ err_bad_call_stack:
 err_empty_call_stack:
 err_dead_binder:
 err_invalid_target_handle:
-       if (target_thread)
-               binder_thread_dec_tmpref(target_thread);
-       if (target_proc)
-               binder_proc_dec_tmpref(target_proc);
        if (target_node) {
                binder_dec_node(target_node, 1, 0);
                binder_dec_node_tmpref(target_node);
@@ -3565,6 +3561,11 @@ err_invalid_target_handle:
                     (u64)tr->data_size, (u64)tr->offsets_size,
                     return_error_line);
 
+       if (target_thread)
+               binder_thread_dec_tmpref(target_thread);
+       if (target_proc)
+               binder_proc_dec_tmpref(target_proc);
+
        {
                struct binder_transaction_log_entry *fe;