From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4E389577E56; Wed, 9 Sep 2026 14:18:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788963500; cv=none; b=jj0/SEF6dDgjXxrLnT9cuYzRNYfxYuHdVdys4EbrlTI7Y4wD3GDR6/5DoT8ge0LupMHl9J6jeHSa+2Ni+ZAxF4Ft0xABTTN0aIjhxTiK28ETEfSbZ8QzYKFKx9PoLVDUTvrt3dikj/Eg0yxWtq21whOUYMI7JTfYghJc22JyGt8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788963500; c=relaxed/simple; bh=BnkReKu4oaAAFjf2/TSEhz/bI4b78f7iUIPPQfm7clY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Px7E6/eP1sEXQlq+VADKbOoj71p18Pjl4u1TUyB/1JZAQf0cX3Bqr/+BnCDNv+CPA5T5vFcAk/a+wURhJaYq3PAN1IDxsVlnM4gD5YQRU/6ygiYBaa54N75+82igrseyFcNXnMgnvYoE/NIrfneoXLU0/LXfj3VPmQgO8ESxdug= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=MPAAkf4k; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="MPAAkf4k" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A48471F00ADB; Wed, 9 Sep 2026 14:18:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788963497; bh=6L+gukhqWjq1HWvQUoMi50FbRc10LFoc1LnEKhxlwZw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=MPAAkf4kEpGPBqHltLSn92mP6tL5aVr3twgp+u123r6RBPExE5hyvl4IcZQ9Wo2// OqkxLEN1rzd3uMHXRSxy6AFqOQwQultHs7ZjAF3AxfNGATw8V0NzJP7L9uykGaZhjX Hu3aZ4zarriGDmd2KuV3C23DlTWUryW0twpfQ2aw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+23ad911c819b923238b7@syzkaller.appspotmail.com, Vasileios Almpanis , Andi Shyti Subject: [PATCH 6.18 099/583] i2c: core: fix debugfs UAF on adapter removal Date: Wed, 9 Sep 2026 15:36:24 +0200 Message-ID: <20260909134241.560209084@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260909134237.773280130@linuxfoundation.org> References: <20260909134237.773280130@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vasileios Almpanis commit b15b548d52b43ba8ac4652bc2c7244a8dd1e9622 upstream. i2c_del_adapter() frees the adapter's debugfs directory before it unregisters the adapter device, but the new_device sysfs attribute stays writable until device_del(). A write racing with removal still reaches i2c_device_probe(), which passes the freed adap->debugfs to debugfs_create_dir() as the new client's parent: BUG: KASAN: slab-use-after-free in lookup_noperm_common+0x407/0x430 Read of size 4 at addr ffff88803ef87810 by task syz.0.61/6090 lookup_noperm_common+0x407/0x430 simple_start_creating+0x9c/0x110 debugfs_start_creating+0xdb/0x1a0 debugfs_create_dir+0x24/0x350 i2c_device_probe+0x814/0xbf0 It's technically possible to create a client after i2c_deregister_clients has run. That client will never be unregistered and make wait_for_completion hang. Close the window by removing the new_device attribute at the start of i2c_del_adapter(). device_remove_file() will drain any clients left. Fixes: 73febd775bdb ("i2c: create debugfs entry per adapter") Reported-by: syzbot+23ad911c819b923238b7@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=23ad911c819b923238b7 Signed-off-by: Vasileios Almpanis Cc: # v6.8+ Tested-by: syzbot+23ad911c819b923238b7@syzkaller.appspotmail.com Signed-off-by: Andi Shyti Link: https://patch.msgid.link/20260812-i2c-v2-1-5efaab4c3334@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/i2c/i2c-core-base.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/drivers/i2c/i2c-core-base.c +++ b/drivers/i2c/i2c-core-base.c @@ -1814,6 +1814,12 @@ void i2c_del_adapter(struct i2c_adapter return; } + /* + * This drains any in-flight writers, so all + * clients will be caught by i2c_deregister_clients(). + */ + device_remove_file(&adap->dev, &dev_attr_new_device); + i2c_acpi_remove_space_handler(adap); i2c_deregister_clients(adap);