From patchwork Fri Sep 13 07:09:28 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: chenridong X-Patchwork-Id: 13803034 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) (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 F05C777107; Fri, 13 Sep 2024 07:17:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.189 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726211860; cv=none; b=RT4mb8QNrt2efQ/bHMRFSf2RYQKy/Am2EVWDwZO+av1EJBOEDfKkDg8M8b1eq3qVq8HwyGKOWMlgzLav9nuW382I3lERVQgspo+mP+ehNn2PbQGC0quxO9V987N8l3hgqzlg9KMuFyCLwZ6N/mRoq7FbqiyxR4KtYZCwJmRFbeg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726211860; c=relaxed/simple; bh=/aB7KyuDzWiiD7QCWbP9P8AiK+96dTijvv1tTPSwsxU=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=thDljgbcocZWqxpvKCycMMjsJkXgaGhSl3H7yIpeBNAs5SZMcxl6G3Pu7hDMf0RyLLRzNIdpOSd4mSu0gNE5EskBk7D4JLl9APUTsAC0TAZdVnnLzbgbAhLpphkYYQiX8awX59FD4zur0e7ydW/jP/sibBU9pEWA0g2tgMH7AqM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.189 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.48]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4X4lxd6Wngz69N3; Fri, 13 Sep 2024 15:17:25 +0800 (CST) Received: from kwepemd100013.china.huawei.com (unknown [7.221.188.163]) by mail.maildlp.com (Postfix) with ESMTPS id 2031518006C; Fri, 13 Sep 2024 15:17:34 +0800 (CST) Received: from huawei.com (10.67.174.121) by kwepemd100013.china.huawei.com (7.221.188.163) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.34; Fri, 13 Sep 2024 15:17:33 +0800 From: Chen Ridong To: , , , , CC: , , , Subject: [PATCH] security/keys: fix slab-out-of-bounds in key_task_permission Date: Fri, 13 Sep 2024 07:09:28 +0000 Message-ID: <20240913070928.1670785-1-chenridong@huawei.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemd100013.china.huawei.com (7.221.188.163) We meet the same issue with the LINK, which reads memory out of bounds: BUG: KASAN: slab-out-of-bounds in __kuid_val include/linux/uidgid.h:36 BUG: KASAN: slab-out-of-bounds in uid_eq include/linux/uidgid.h:63 [inline] BUG: KASAN: slab-out-of-bounds in key_task_permission+0x394/0x410 security/keys/permission.c:54 Read of size 4 at addr ffff88813c3ab618 by task stress-ng/4362 CPU: 2 PID: 4362 Comm: stress-ng Not tainted 5.10.0-14930-gafbffd6c3ede #15 Call Trace: __dump_stack lib/dump_stack.c:82 [inline] dump_stack+0x107/0x167 lib/dump_stack.c:123 print_address_description.constprop.0+0x19/0x170 mm/kasan/report.c:400 __kasan_report.cold+0x6c/0x84 mm/kasan/report.c:560 kasan_report+0x3a/0x50 mm/kasan/report.c:585 __kuid_val include/linux/uidgid.h:36 [inline] uid_eq include/linux/uidgid.h:63 [inline] key_task_permission+0x394/0x410 security/keys/permission.c:54 search_nested_keyrings+0x90e/0xe90 security/keys/keyring.c:793 keyring_search_rcu+0x1b6/0x310 security/keys/keyring.c:922 search_cred_keyrings_rcu+0x111/0x2e0 security/keys/process_keys.c:459 search_process_keyrings_rcu+0x1d/0x310 security/keys/process_keys.c:544 lookup_user_key+0x782/0x12e0 security/keys/process_keys.c:762 keyctl_invalidate_key+0x20/0x190 security/keys/keyctl.c:434 __do_sys_keyctl security/keys/keyctl.c:1978 [inline] __se_sys_keyctl+0x1de/0x5b0 security/keys/keyctl.c:1880 do_syscall_64+0x30/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x67/0xd1 However, we can't reproduce this issue. After our analysis, it can make this issue by following steps. 1.As syzkaller reported, the memory is allocated for struct assoc_array_shortcut in the assoc_array_insert_into_terminal_node functions. 2.In the search_nested_keyrings, when we go through the slots in a node, (bellow tag ascend_to_node), and the slot ptr is meta and node->back_pointer != NULL, we will proceed to descend_to_node. However, there is an exception. If node is the root, and one of the slots points to a shortcut, it will be treated as a keyring. 3.Whether the ptr is keyring decided by keyring_ptr_is_keyring function. However, KEYRING_PTR_SUBTYPE is 0x2UL, the same as ASSOC_ARRAY_PTR_SUBTYPE_MASK, 4.As mentioned above, If a slot of the root is a shortcut, it may be mistakenly be transferred to a key*, leading to an read out-of-bounds read. To fix this issue, one should jump to descend_to_node if the pointer is a shortcut. Link: https://syzkaller.appspot.com/bug?id=68a5e206c2a8e08d317eb83f05610c0484ad10b9 Fixes: b2a4df200d57 ("KEYS: Expand the capacity of a keyring") Signed-off-by: Chen Ridong --- security/keys/keyring.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/security/keys/keyring.c b/security/keys/keyring.c index 4448758f643a..7958486ac834 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -772,7 +772,9 @@ static bool search_nested_keyrings(struct key *keyring, for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) { ptr = READ_ONCE(node->slots[slot]); - if (assoc_array_ptr_is_meta(ptr) && node->back_pointer) + if ((assoc_array_ptr_is_meta(ptr) && node->back_pointer) || + (assoc_array_ptr_is_meta(ptr) && + assoc_array_ptr_is_shortcut(ptr))) goto descend_to_node; if (!keyring_ptr_is_keyring(ptr))