From nobody Tue Feb 10 15:43:50 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AEACFC77B7A for ; Fri, 19 May 2023 16:14:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229514AbjESQOe (ORCPT ); Fri, 19 May 2023 12:14:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45192 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229673AbjESQOZ (ORCPT ); Fri, 19 May 2023 12:14:25 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4F0451702; Fri, 19 May 2023 09:14:11 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A1D2F658E3; Fri, 19 May 2023 16:14:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6892EC433D2; Fri, 19 May 2023 16:14:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1684512850; bh=TwVB5CNSXyBVdSL/6LkxFooRKToo+KuulE1fK+6TWiU=; h=From:To:Cc:Subject:Date:From; b=an6dx7WYENUIuO0UUU/CeaARtR2AEC8jO0IdQfgoTVS9HnvSu8QKBaZriuhSPFqum o7MWw7/5CaDgT7t5JNyiNZ5k6rMVyTbPFVx1bvlQWElr8JInoYxFY4eHEtzJoDJs2+ fwM12wF7I59VKlvT5VNTmPuhgVnqcAp5c1Q9Z5KH0MObXvxLHkpmQWZQxlFmIpa7TG G0NtQnFGZuIMeuq465DNgSP6F7teQfyIEo13XtQs53kF3AQL04Qrqek3xVviMHb3Cc GbWGJy0xvU7HyVThstPYl08kMJQenGhVTnq0RULwripMuadfBEBkMfzTJLg2uFE2Qy 1W6gBLo2PxmAQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Lee Jones , Jassi Brar , Sasha Levin , jassisinghbrar@gmail.com Subject: [PATCH AUTOSEL 4.14] mailbox: mailbox-test: Fix potential double-free in mbox_test_message_write() Date: Fri, 19 May 2023 12:14:07 -0400 Message-Id: <20230519161407.2757637-1-sashal@kernel.org> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Lee Jones [ Upstream commit 2d1e952a2b8e5e92d8d55ac88a7cf7ca5ea591ad ] If a user can make copy_from_user() fail, there is a potential for UAF/DF due to a lack of locking around the allocation, use and freeing of the data buffers. This issue is not theoretical. I managed to author a POC for it: BUG: KASAN: double-free in kfree+0x5c/0xac Free of addr ffff29280be5de00 by task poc/356 CPU: 1 PID: 356 Comm: poc Not tainted 6.1.0-00001-g961aa6552c04-dirty #= 20 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace.part.0+0xe0/0xf0 show_stack+0x18/0x40 dump_stack_lvl+0x64/0x80 print_report+0x188/0x48c kasan_report_invalid_free+0xa0/0xc0 ____kasan_slab_free+0x174/0x1b0 __kasan_slab_free+0x18/0x24 __kmem_cache_free+0x130/0x2e0 kfree+0x5c/0xac mbox_test_message_write+0x208/0x29c full_proxy_write+0x90/0xf0 vfs_write+0x154/0x440 ksys_write+0xcc/0x180 __arm64_sys_write+0x44/0x60 invoke_syscall+0x60/0x190 el0_svc_common.constprop.0+0x7c/0x160 do_el0_svc+0x40/0xf0 el0_svc+0x2c/0x6c el0t_64_sync_handler+0xf4/0x120 el0t_64_sync+0x18c/0x190 Allocated by task 356: kasan_save_stack+0x3c/0x70 kasan_set_track+0x2c/0x40 kasan_save_alloc_info+0x24/0x34 __kasan_kmalloc+0xb8/0xc0 kmalloc_trace+0x58/0x70 mbox_test_message_write+0x6c/0x29c full_proxy_write+0x90/0xf0 vfs_write+0x154/0x440 ksys_write+0xcc/0x180 __arm64_sys_write+0x44/0x60 invoke_syscall+0x60/0x190 el0_svc_common.constprop.0+0x7c/0x160 do_el0_svc+0x40/0xf0 el0_svc+0x2c/0x6c el0t_64_sync_handler+0xf4/0x120 el0t_64_sync+0x18c/0x190 Freed by task 357: kasan_save_stack+0x3c/0x70 kasan_set_track+0x2c/0x40 kasan_save_free_info+0x38/0x5c ____kasan_slab_free+0x13c/0x1b0 __kasan_slab_free+0x18/0x24 __kmem_cache_free+0x130/0x2e0 kfree+0x5c/0xac mbox_test_message_write+0x208/0x29c full_proxy_write+0x90/0xf0 vfs_write+0x154/0x440 ksys_write+0xcc/0x180 __arm64_sys_write+0x44/0x60 invoke_syscall+0x60/0x190 el0_svc_common.constprop.0+0x7c/0x160 do_el0_svc+0x40/0xf0 el0_svc+0x2c/0x6c el0t_64_sync_handler+0xf4/0x120 el0t_64_sync+0x18c/0x190 Signed-off-by: Lee Jones Signed-off-by: Jassi Brar Signed-off-by: Sasha Levin --- drivers/mailbox/mailbox-test.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/mailbox/mailbox-test.c b/drivers/mailbox/mailbox-test.c index 546ba140f83d2..c23acd994d783 100644 --- a/drivers/mailbox/mailbox-test.c +++ b/drivers/mailbox/mailbox-test.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include #include @@ -43,6 +44,7 @@ struct mbox_test_device { char *signal; char *message; spinlock_t lock; + struct mutex mutex; wait_queue_head_t waitq; struct fasync_struct *async_queue; }; @@ -114,6 +116,8 @@ static ssize_t mbox_test_message_write(struct file *fil= p, return -EINVAL; } =20 + mutex_lock(&tdev->mutex); + tdev->message =3D kzalloc(MBOX_MAX_MSG_LEN, GFP_KERNEL); if (!tdev->message) return -ENOMEM; @@ -148,6 +152,8 @@ static ssize_t mbox_test_message_write(struct file *fil= p, kfree(tdev->message); tdev->signal =3D NULL; =20 + mutex_unlock(&tdev->mutex); + return ret < 0 ? ret : count; } =20 @@ -396,6 +402,7 @@ static int mbox_test_probe(struct platform_device *pdev) platform_set_drvdata(pdev, tdev); =20 spin_lock_init(&tdev->lock); + mutex_init(&tdev->mutex); =20 if (tdev->rx_channel) { tdev->rx_buffer =3D devm_kzalloc(&pdev->dev, --=20 2.39.2