* [PATCH] binder: fix potential UAF of target_{proc,thread}
@ 2022-05-17 18:58 Carlos Llamas
2022-05-17 19:18 ` Todd Kjos
0 siblings, 1 reply; 2+ messages in thread
From: Carlos Llamas @ 2022-05-17 18:58 UTC (permalink / raw)
To: Greg Kroah-Hartman, Arve Hjønnevåg, Todd Kjos,
Martijn Coenen, Christian Brauner
Cc: Joel Fernandes, Hridya Valsaraju, Suren Baghdasaryan,
kernel-team, linux-kernel, Dan Carpenter, Carlos Llamas
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>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
---
drivers/android/binder.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index d9253b2a7bd9..83facfa1a5c3 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -3546,10 +3546,6 @@ static void binder_transaction(struct binder_proc *proc,
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 @@ static void binder_transaction(struct binder_proc *proc,
(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;
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] binder: fix potential UAF of target_{proc,thread}
2022-05-17 18:58 [PATCH] binder: fix potential UAF of target_{proc,thread} Carlos Llamas
@ 2022-05-17 19:18 ` Todd Kjos
0 siblings, 0 replies; 2+ messages in thread
From: Todd Kjos @ 2022-05-17 19:18 UTC (permalink / raw)
To: Carlos Llamas
Cc: Greg Kroah-Hartman, Arve Hjønnevåg, Todd Kjos,
Martijn Coenen, Christian Brauner, Joel Fernandes,
Hridya Valsaraju, Suren Baghdasaryan, kernel-team, linux-kernel,
Dan Carpenter
On Tue, May 17, 2022 at 11:58 AM Carlos Llamas <cmllamas@google.com> wrote:
>
> 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>
> Signed-off-by: Carlos Llamas <cmllamas@google.com>
Acked-by: Todd Kjos <tkjos@google.com>
> ---
> drivers/android/binder.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/android/binder.c b/drivers/android/binder.c
> index d9253b2a7bd9..83facfa1a5c3 100644
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -3546,10 +3546,6 @@ static void binder_transaction(struct binder_proc *proc,
> 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 @@ static void binder_transaction(struct binder_proc *proc,
> (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;
>
> --
> 2.36.0.550.gb090851708-goog
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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