From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (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 83D1D21A420 for ; Mon, 15 Sep 2025 22:50:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757976640; cv=none; b=sM74Y/iU2Ed40HK3RJ6hDrJpLnjqLA7uKHgJRcy/hmZ1WPuyur53iY7aJgB8yeD9YTck85ICEYwKeQ7eS2qWeO0x6ufovVwt0ty+PjzMf2eo54GCFhYwHCiCSHQ4Lnr1sK9eCDNc3OnLzx2lH1pmZkCamHMuTs71FaDel5h+NJs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757976640; c=relaxed/simple; bh=7XUcFdyi5pghNDqYShPZlZf5FW9PbMiBbI2R59AvwA8=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=HIHvpnRdvxsefP2ys+MClx2i3KRtInRyAg9SMUpG+Fdrezs9G2mdtrIojIDkW0Z0j+S0VsO36icVpyxXm1Q9ZA/O5KyvuxB3P3a5JbMAMIzjjTX6aA6YkFzqdOJcBgjCzifqQKY5reHkNB3hOc6B2+/KXqIplJHDeFArDUNIoCM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--ynaffit.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=phSRlIB9; arc=none smtp.client-ip=209.85.214.202 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--ynaffit.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="phSRlIB9" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-24457f59889so48359395ad.0 for ; Mon, 15 Sep 2025 15:50:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1757976639; x=1758581439; darn=vger.kernel.org; h=cc:to:from:subject:message-id:user-agent:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to; bh=FHCYBGzmS+VHS2LiTQcupGZB9njnywXUSm+3JCgstqg=; b=phSRlIB9fD4gXp+Zy40KyrcyUiBev4gwgSUoJptNyN5W54FHoZ23Mz+d9Vu0OCsM3t uyQxPzacIub4ayA4Hwn0em4TKWiT61s9ZS6WaqT+SU1IVAbP2Gn+Ax6vkEeIaoeBKlmx fYDqrhrZ4d2FdeHXhbuCYoDriH8jVi33KHeEpfd2APSj17Yl/pqI0N0e4cNRhkLOZSyG Wxy7b3jLenkTY4VnYfmwGXrJ4IThE8axVFewjklCAP9EEpKDfTBBALllHqMYUXaaNbD6 0T9gE2PKSOhD/33g4cSxPVtaaGCrYTp1xMZ7e2RNDfmhRv2/VO4cFr8c4If8B0PdwbBb DHnA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1757976639; x=1758581439; h=cc:to:from:subject:message-id:user-agent:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=FHCYBGzmS+VHS2LiTQcupGZB9njnywXUSm+3JCgstqg=; b=ohmsAiumrJiOD0Vqp8geN2NT81/dAoCfL7JQkGCNN0Umsi7Qne1PdAksaft5uFdIlV EhdZrueguhabAUg2WfqjFWDfcl+BV0qCDU7qT1OREMsKrmyjRL84RsNqpaBAxP0MNADF GKCIkKLUxgOXHHrAo86Wapc+zlq+0AKX9EFk0kstlt5FWzE19iPEFEejGguxlvesp+vV CvgkCVlmgq9CZ9vlwzCvsn2o5tP8wpsKLtLrMe+jg9m20P+VJKElZ8RzxRnRndNZ0ITv 65efZkUC0IxRcSSy7QgY6h6Gs1XHSRIgAnmoeooVBpE6tFZN0bI+WB+I9tX0M9MVvRdv DiPw== X-Forwarded-Encrypted: i=1; AJvYcCV8yB9Ev+Gas3g0cD51UkkdJfURZ1jPUoMpEARowNsGd7gBCZuVKzg430gQRL+Sf9BX14i5+6E=@vger.kernel.org X-Gm-Message-State: AOJu0Yy9dBq+OtB7X144TWHrC5so43xpVV2jr/8Q0lmp7mdVrzAnw+t6 Ky8MSjr3xKKGA+QOeCJtHM65bA+lcJrU7uYXJFmp1szs29kGBfk7AnZLKkDkMVi5iQOMM3thUiE wKTPlJj9z1g== X-Google-Smtp-Source: AGHT+IE6hbDx6V/jMsnsms/qKiIlFQPmNSNP/cWma2PRVBTnkAUf3QF90DV5CUSA3kwoSWRzABSKSW2f8m9J X-Received: from pjbsz5.prod.google.com ([2002:a17:90b:2d45:b0:32b:6136:95b9]) (user=ynaffit job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:32c9:b0:267:bd8d:1a0 with SMTP id d9443c01a7336-267bd8d09dfmr14585835ad.13.1757976638706; Mon, 15 Sep 2025 15:50:38 -0700 (PDT) Date: Mon, 15 Sep 2025 15:50:37 -0700 In-Reply-To: <20250915221248.3470154-1-cmllamas@google.com> (Carlos Llamas's message of "Mon, 15 Sep 2025 22:12:47 +0000") Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250915221248.3470154-1-cmllamas@google.com> User-Agent: mu4e 1.12.9; emacs 30.1 Message-ID: Subject: Re: [PATCH] binder: fix double-free in dbitmap From: Tiffany Yang To: Carlos Llamas Cc: Greg Kroah-Hartman , "=?utf-8?Q?Arve_Hj?= =?utf-8?Q?=C3=B8nnev=C3=A5g?=" , Todd Kjos , Martijn Coenen , Joel Fernandes , Christian Brauner , Suren Baghdasaryan , Alice Ryhl , kernel-team@android.com, linux-kernel@vger.kernel.org, stable@vger.kernel.org Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes Carlos Llamas writes: > A process might fail to allocate a new bitmap when trying to expand its > proc->dmap. In that case, dbitmap_grow() fails and frees the old bitmap > via dbitmap_free(). However, the driver calls dbitmap_free() again when > the same process terminates, leading to a double-free error: > ================================================================== > BUG: KASAN: double-free in binder_proc_dec_tmpref+0x2e0/0x55c > Free of addr ffff00000b7c1420 by task kworker/9:1/209 > CPU: 9 UID: 0 PID: 209 Comm: kworker/9:1 Not tainted 6.17.0-rc6-dirty > #5 PREEMPT > Hardware name: linux,dummy-virt (DT) > Workqueue: events binder_deferred_func > Call trace: > kfree+0x164/0x31c > binder_proc_dec_tmpref+0x2e0/0x55c > binder_deferred_func+0xc24/0x1120 > process_one_work+0x520/0xba4 > [...] > Allocated by task 448: > __kmalloc_noprof+0x178/0x3c0 > bitmap_zalloc+0x24/0x30 > binder_open+0x14c/0xc10 > [...] > Freed by task 449: > kfree+0x184/0x31c > binder_inc_ref_for_node+0xb44/0xe44 > binder_transaction+0x29b4/0x7fbc > binder_thread_write+0x1708/0x442c > binder_ioctl+0x1b50/0x2900 > [...] > ================================================================== > Fix this issue by marking proc->map NULL in dbitmap_free(). > Cc: stable@vger.kernel.org > Fixes: 15d9da3f818c ("binder: use bitmap for faster descriptor lookup") > Signed-off-by: Carlos Llamas > --- > drivers/android/dbitmap.h | 1 + > 1 file changed, 1 insertion(+) > diff --git a/drivers/android/dbitmap.h b/drivers/android/dbitmap.h > index 956f1bd087d1..c7299ce8b374 100644 > --- a/drivers/android/dbitmap.h > +++ b/drivers/android/dbitmap.h > @@ -37,6 +37,7 @@ static inline void dbitmap_free(struct dbitmap *dmap) > { > dmap->nbits = 0; > kfree(dmap->map); > + dmap->map = NULL; > } > /* Returns the nbits that a dbitmap can shrink to, 0 if not possible. */ Reviewed-by: Tiffany Yang -- Tiffany Y. Yang