From nobody Sat Feb 7 17:20:04 2026 Received: from mail-dl1-f73.google.com (mail-dl1-f73.google.com [74.125.82.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 006BA48AE28 for ; Wed, 21 Jan 2026 14:50:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769007029; cv=none; b=qK5ptF7KnOmnK70AAlsmCBD6GKflJvniLV/GrvMfikCuT29meTB2Bw1dwNoA/Cdzh3y8t8/+e3tvK0zY9+AOKIu+xOfbCV1JbVNWGnMhvVmiAC8uvQvT6z7x78GksWKphNlGuCsmmG69SWb7BhYtT4dP47wIQtHQX66BQbJFmWE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769007029; c=relaxed/simple; bh=blsOvSu+NsTlGasp6WKVyqG0n743f0kngtoxvejq31g=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=RyCx6k4x2BPq+c9dKWmuOdmnKsaw7RW396LeXq7wOHVyarF2g8xlaNIkdROPgtCO9JcxbXe555kOgbFJNnjBEUfjKDMcAE4IQpGa7pEVESjluBHEfgxce2hyUJ6h0+Kx0RsrzzqUT6/U97JNLhnv2lk3HHpWyUHsEzlBasLHRN4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--cmllamas.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=ZJrd/0D2; arc=none smtp.client-ip=74.125.82.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--cmllamas.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="ZJrd/0D2" Received: by mail-dl1-f73.google.com with SMTP id a92af1059eb24-124743cf760so1198427c88.1 for ; Wed, 21 Jan 2026 06:50:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1769007026; x=1769611826; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=euAK2if6pWi2IvG5zRCjntEoGbMw8B6pYC9dKG2JFHU=; b=ZJrd/0D2nvOBtVTRDXrZ4rtwHP9ZNM7xpjM2CWlSH26tFw+UqLmgfw3JRbhzBe2OVX Fv3mkxho6cMMABFdQ/RMPNGLgd5BeVhu2eam3rYGu7C+Q9I6jpZpW/Q8SW+cg8g/9QRh clOpAn23Jsnm+t5Ol6m485O8bQjMvoWSaxMEkhmo46LdsN7nGZRXhCkSxa6RCOiFNis7 D5K0nPeYuQi+hExZN2X/WeVNnFgXmCbzCpqshe6yO449ZDHvyoxNw7emcvym8Xrx/TCv ddAEnqpJaKwdbi4IBBYE9bm6OPtiWxkKqMjFPeOWemUGufPDonV4JSop6XspdfkAKqV6 OprQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769007026; x=1769611826; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=euAK2if6pWi2IvG5zRCjntEoGbMw8B6pYC9dKG2JFHU=; b=lNW513ZabREEX0Afce0Bg7bN/Ij+A8jKWzZ8a6w453y1Ht/ol9sG6B05OupR7Cs2Ep 63eqy3+8eRopG4v1ZKY1crGFKgP71wv36VVI2iWhb4oFDjNewDAa02Vi+WrfXNxHYMAJ Mj9zT/49DyK84N4QakLv7XiRJuXbSW1lps04IlVPzTrBMN2hq+Zi/QxNXGVAb7gEdKPY nOO3nKA2z2C1TIFx25g0zF4hfpuH9XKNfJOxokmSDA9DWXD1Lc/MSe4bida8zYX76NU4 1lqA0bGyuNL2BSk51ocPneTlaVZfJC3bjs1T7OViFARAZAUGmM/4C0AkHVlyGO2dE4Xi 0rYw== X-Forwarded-Encrypted: i=1; AJvYcCU1dZCMkdFW52QETgO95sFGxXFaBXvrOxxFUsuHXd/ki8VPkvgE3S8MgfT7OsK7SlrdWiNLy362Uo57j7Q=@vger.kernel.org X-Gm-Message-State: AOJu0YxwN4lcYmG9FUOTdIBh+z4yszEQ8wudq044OwpRsDulXmmae/Jp wwu6vN1qlRggyLpTGW/6lqbmO+QFpG4aahK0gNb/x16sGzLaprnZ0X6TwKHguwnlcYkBcgcsuip qObvqUMgUr3pzvQ== X-Received: from dlbpy14.prod.google.com ([2002:a05:7022:e98e:b0:11d:cfa0:5ddf]) (user=cmllamas job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7022:7a7:b0:11d:f44c:afbc with SMTP id a92af1059eb24-1246aadcce9mr4085014c88.37.1769007025887; Wed, 21 Jan 2026 06:50:25 -0800 (PST) Date: Wed, 21 Jan 2026 14:50:04 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.52.0.457.g6b5491de43-goog Message-ID: <20260121145005.120507-1-cmllamas@google.com> Subject: [PATCH] binder: fix UAF in binder_netlink_report() From: Carlos Llamas To: Greg Kroah-Hartman , "=?UTF-8?q?Arve=20Hj=C3=B8nnev=C3=A5g?=" , Todd Kjos , Christian Brauner , Carlos Llamas , Alice Ryhl , Li Li Cc: kernel-team@android.com, linux-kernel@vger.kernel.org, stable@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Oneway transactions sent to frozen targets via binder_proc_transaction() return a BR_TRANSACTION_PENDING_FROZEN error but they are still treated as successful since the target is expected to thaw at some point. It is then not safe to access 't' after BR_TRANSACTION_PENDING_FROZEN errors as the transaction could have been consumed by the now thawed target. This is the case for binder_netlink_report() which derreferences 't' after a pending frozen error, as pointed out by the following KASAN report: =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D BUG: KASAN: slab-use-after-free in binder_netlink_report.isra.0+0x694/0x6= c8 Read of size 8 at addr ffff00000f98ba38 by task binder-util/522 CPU: 4 UID: 0 PID: 522 Comm: binder-util Not tainted 6.19.0-rc6-00015-gc0= 3e9c42ae8f #1 PREEMPT Hardware name: linux,dummy-virt (DT) Call trace: binder_netlink_report.isra.0+0x694/0x6c8 binder_transaction+0x66e4/0x79b8 binder_thread_write+0xab4/0x4440 binder_ioctl+0x1fd4/0x2940 [...] Allocated by task 522: __kmalloc_cache_noprof+0x17c/0x50c binder_transaction+0x584/0x79b8 binder_thread_write+0xab4/0x4440 binder_ioctl+0x1fd4/0x2940 [...] Freed by task 488: kfree+0x1d0/0x420 binder_free_transaction+0x150/0x234 binder_thread_read+0x2d08/0x3ce4 binder_ioctl+0x488/0x2940 [...] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Instead, make a transaction copy so the data can be safely accessed by binder_netlink_report() after a pending frozen error. Cc: stable@vger.kernel.org Fixes: 63740349eba7 ("binder: introduce transaction reports via netlink") Signed-off-by: Carlos Llamas --- drivers/android/binder.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 535fc881c8da..70dc63a6e06a 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -3780,6 +3780,14 @@ static void binder_transaction(struct binder_proc *p= roc, goto err_dead_proc_or_thread; } } else { + /* + * Make a transaction copy. It is not safe to access 't' after + * binder_proc_transaction() reported a pending frozen. The + * target could thaw and consume the transaction at any point. + * Instead, use a safe 't_copy' for binder_netlink_report(). + */ + struct binder_transaction t_copy =3D *t; + BUG_ON(target_node =3D=3D NULL); BUG_ON(t->buffer->async_transaction !=3D 1); return_error =3D binder_proc_transaction(t, target_proc, NULL); @@ -3790,7 +3798,7 @@ static void binder_transaction(struct binder_proc *pr= oc, */ if (return_error =3D=3D BR_TRANSACTION_PENDING_FROZEN) { tcomplete->type =3D BINDER_WORK_TRANSACTION_PENDING; - binder_netlink_report(proc, t, tr->data_size, + binder_netlink_report(proc, &t_copy, tr->data_size, return_error); } binder_enqueue_thread_work(thread, tcomplete); --=20 2.52.0.457.g6b5491de43-goog