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From: Jann Horn <jannh@google.com>
To: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Arve Hjønnevåg" <arve@android.com>,
	"Todd Kjos" <tkjos@android.com>,
	"Martijn Coenen" <maco@android.com>,
	"Joel Fernandes" <joel@joelfernandes.org>,
	"Christian Brauner" <christian@brauner.io>,
	"Hridya Valsaraju" <hridya@google.com>,
	"Suren Baghdasaryan" <surenb@google.com>
Cc: devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org
Subject: [PATCH] binder: Remove bogus warning on failed same-process transaction
Date: Thu,  6 Aug 2020 18:53:59 +0200	[thread overview]
Message-ID: <20200806165359.2381483-1-jannh@google.com> (raw)

While binder transactions with the same binder_proc as sender and recipient
are forbidden, transactions with the same task_struct as sender and
recipient are possible (even though currently there is a weird check in
binder_transaction() that rejects them in the target==0 case).
Therefore, task_struct identities can't be used to distinguish whether
the caller is running in the context of the sender or the recipient.

Since I see no easy way to make this WARN_ON() useful and correct, let's
just remove it.

Fixes: 44d8047f1d87 ("binder: use standard functions to allocate fds")
Reported-by: syzbot+e113a0b970b7b3f394ba@syzkaller.appspotmail.com
Signed-off-by: Jann Horn <jannh@google.com>
---
 drivers/android/binder.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index f936530a19b0..5b0376344dbe 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -2344,8 +2344,6 @@ static void binder_transaction_buffer_release(struct binder_proc *proc,
 			 * file is done when the transaction is torn
 			 * down.
 			 */
-			WARN_ON(failed_at &&
-				proc->tsk == current->group_leader);
 		} break;
 		case BINDER_TYPE_PTR:
 			/*

base-commit: 47ec5303d73ea344e84f46660fff693c57641386
-- 
2.28.0.163.g6104cc2f0b6-goog


WARNING: multiple messages have this Message-ID (diff)
From: Jann Horn <jannh@google.com>
To: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Arve Hjønnevåg" <arve@android.com>,
	"Todd Kjos" <tkjos@android.com>,
	"Martijn Coenen" <maco@android.com>,
	"Joel Fernandes" <joel@joelfernandes.org>,
	"Christian Brauner" <christian@brauner.io>,
	"Hridya Valsaraju" <hridya@google.com>,
	"Suren Baghdasaryan" <surenb@google.com>
Cc: devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org
Subject: [PATCH] binder: Remove bogus warning on failed same-process transaction
Date: Thu,  6 Aug 2020 18:53:59 +0200	[thread overview]
Message-ID: <20200806165359.2381483-1-jannh@google.com> (raw)

While binder transactions with the same binder_proc as sender and recipient
are forbidden, transactions with the same task_struct as sender and
recipient are possible (even though currently there is a weird check in
binder_transaction() that rejects them in the target==0 case).
Therefore, task_struct identities can't be used to distinguish whether
the caller is running in the context of the sender or the recipient.

Since I see no easy way to make this WARN_ON() useful and correct, let's
just remove it.

Fixes: 44d8047f1d87 ("binder: use standard functions to allocate fds")
Reported-by: syzbot+e113a0b970b7b3f394ba@syzkaller.appspotmail.com
Signed-off-by: Jann Horn <jannh@google.com>
---
 drivers/android/binder.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index f936530a19b0..5b0376344dbe 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -2344,8 +2344,6 @@ static void binder_transaction_buffer_release(struct binder_proc *proc,
 			 * file is done when the transaction is torn
 			 * down.
 			 */
-			WARN_ON(failed_at &&
-				proc->tsk == current->group_leader);
 		} break;
 		case BINDER_TYPE_PTR:
 			/*

base-commit: 47ec5303d73ea344e84f46660fff693c57641386
-- 
2.28.0.163.g6104cc2f0b6-goog

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             reply	other threads:[~2020-08-06 16:54 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-06 16:53 Jann Horn [this message]
2020-08-06 16:53 ` [PATCH] binder: Remove bogus warning on failed same-process transaction Jann Horn
2020-08-06 16:58 ` Todd Kjos
2020-08-06 16:58   ` Todd Kjos
2020-08-07 14:06 ` Christian Brauner
2020-08-07 14:06   ` Christian Brauner

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