From nobody Fri Sep 5 20:25:39 2025 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 36D93C32796 for ; Tue, 23 Aug 2022 11:37:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345775AbiHWLh3 (ORCPT ); Tue, 23 Aug 2022 07:37:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49384 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1357693AbiHWLbv (ORCPT ); Tue, 23 Aug 2022 07:31:51 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8779176742; Tue, 23 Aug 2022 02:25:58 -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 ams.source.kernel.org (Postfix) with ESMTPS id C7DC2B81B1F; Tue, 23 Aug 2022 09:25:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2AE06C433D6; Tue, 23 Aug 2022 09:25:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661246755; bh=EfWtyByjgytpa+fc7uz7HY80Ck6qDvLpgj0zv4ySv9A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YsIvx3IAgxyX5JJLCiT3xMzr5b26i7lVRD1b6Bvgt6tLnjMpCiTaTey/efguTA9y8 30WHiKAmMQ2wTUzFO2MaA4Lfl2kuHSk+zWA8stp9fm2zEkhMJymrQcOOBTY3EVJ2g4 CyoWWgkSk8T7huMN6gzuU8fNWx0ipiduQRTOCOmM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Chen Zhongjin , Andrew Morton , Sasha Levin Subject: [PATCH 5.4 210/389] profiling: fix shift too large makes kernel panic Date: Tue, 23 Aug 2022 10:24:48 +0200 Message-Id: <20220823080124.395999731@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220823080115.331990024@linuxfoundation.org> References: <20220823080115.331990024@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 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: Chen Zhongjin [ Upstream commit 0fe6ee8f123a4dfb529a5aff07536bb481f34043 ] 2d186afd04d6 ("profiling: fix shift-out-of-bounds bugs") limits shift value by [0, BITS_PER_LONG -1], which means [0, 63]. However, syzbot found that the max shift value should be the bit number of (_etext - _stext). If shift is outside of this, the "buffer_bytes" will be zero and will cause kzalloc(0). Then the kernel panics due to dereferencing the returned pointer 16. This can be easily reproduced by passing a large number like 60 to enable profiling and then run readprofile. LOGS: BUG: kernel NULL pointer dereference, address: 0000000000000010 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 6148067 P4D 6148067 PUD 6142067 PMD 0 PREEMPT SMP CPU: 4 PID: 184 Comm: readprofile Not tainted 5.18.0+ #162 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g= 2dd4b9b3f840-prebuilt.qemu.org 04/01/2014 RIP: 0010:read_profile+0x104/0x220 RSP: 0018:ffffc900006fbe80 EFLAGS: 00000202 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff888006150000 RSI: 0000000000000001 RDI: ffffffff82aba4a0 RBP: 000000000188bb60 R08: 0000000000000010 R09: ffff888006151000 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff82aba4a0 R13: 0000000000000000 R14: ffffc900006fbf08 R15: 0000000000020c30 FS: 000000000188a8c0(0000) GS:ffff88803ed00000(0000) knlGS:00000000000000= 00 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000010 CR3: 0000000006144000 CR4: 00000000000006e0 Call Trace: proc_reg_read+0x56/0x70 vfs_read+0x9a/0x1b0 ksys_read+0xa1/0xe0 ? fpregs_assert_state_consistent+0x1e/0x40 do_syscall_64+0x3a/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x4d4b4e RSP: 002b:00007ffebb668d58 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 000000000188a8a0 RCX: 00000000004d4b4e RDX: 0000000000000400 RSI: 000000000188bb60 RDI: 0000000000000003 RBP: 0000000000000003 R08: 000000000000006e R09: 0000000000000000 R10: 0000000000000041 R11: 0000000000000246 R12: 000000000188bb60 R13: 0000000000000400 R14: 0000000000000000 R15: 000000000188bb60 Modules linked in: CR2: 0000000000000010 Killed ---[ end trace 0000000000000000 ]--- Check prof_len in profile_init() to prevent it be zero. Link: https://lkml.kernel.org/r/20220531012854.229439-1-chenzhongjin@huawei= .com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Chen Zhongjin Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin --- kernel/profile.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/profile.c b/kernel/profile.c index e97e42aaf202..b5ce18b6f1b9 100644 --- a/kernel/profile.c +++ b/kernel/profile.c @@ -109,6 +109,13 @@ int __ref profile_init(void) =20 /* only text is profiled */ prof_len =3D (_etext - _stext) >> prof_shift; + + if (!prof_len) { + pr_warn("profiling shift: %u too large\n", prof_shift); + prof_on =3D 0; + return -EINVAL; + } + buffer_bytes =3D prof_len*sizeof(atomic_t); =20 if (!alloc_cpumask_var(&prof_cpu_mask, GFP_KERNEL)) --=20 2.35.1