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[23.128.96.18]) by mx.google.com with ESMTP id b14si8830699eds.379.2021.04.03.04.55.36; Sat, 03 Apr 2021 04:55:58 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236672AbhDCLw0 (ORCPT + 99 others); Sat, 3 Apr 2021 07:52:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39326 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236765AbhDCLwW (ORCPT ); Sat, 3 Apr 2021 07:52:22 -0400 Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C2A46C061788 for ; Sat, 3 Apr 2021 04:52:19 -0700 (PDT) Received: by ozlabs.org (Postfix, from userid 1034) id 4FCFdr5WjMz9sW0; Sat, 3 Apr 2021 22:52:16 +1100 (AEDT) From: Michael Ellerman To: Christophe Leroy , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org In-Reply-To: References: Subject: Re: [PATCH v2] powerpc/signal32: Fix Oops on sigreturn with unmapped VDSO Message-Id: <161745070541.936361.6883787979113499379.b4-ty@ellerman.id.au> Date: Sat, 03 Apr 2021 22:51:45 +1100 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 31 Mar 2021 14:07:04 +0000 (UTC), Christophe Leroy wrote: > PPC32 encounters a KUAP fault when trying to handle a signal with > VDSO unmapped. > > Kernel attempted to read user page (7fc07ec0) - exploit attempt? (uid: 0) > BUG: Unable to handle kernel data access on read at 0x7fc07ec0 > Faulting instruction address: 0xc00111d4 > Oops: Kernel access of bad area, sig: 11 [#1] > BE PAGE_SIZE=16K PREEMPT CMPC885 > CPU: 0 PID: 353 Comm: sigreturn_vdso Not tainted 5.12.0-rc4-s3k-dev-01553-gb30c310ea220 #4814 > NIP: c00111d4 LR: c0005a28 CTR: 00000000 > REGS: cadb3dd0 TRAP: 0300 Not tainted (5.12.0-rc4-s3k-dev-01553-gb30c310ea220) > MSR: 00009032 CR: 48000884 XER: 20000000 > DAR: 7fc07ec0 DSISR: 88000000 > GPR00: c0007788 cadb3e90 c28d4a40 7fc07ec0 7fc07ed0 000004e0 7fc07ce0 00000000 > GPR08: 00000001 00000001 7fc07ec0 00000000 28000282 1001b828 100a0920 00000000 > GPR16: 100cac0c 100b0000 105c43a4 105c5685 100d0000 100d0000 100d0000 100b2e9e > GPR24: ffffffff 105c43c8 00000000 7fc07ec8 cadb3f40 cadb3ec8 c28d4a40 00000000 > NIP [c00111d4] flush_icache_range+0x90/0xb4 > LR [c0005a28] handle_signal32+0x1bc/0x1c4 > Call Trace: > [cadb3e90] [100d0000] 0x100d0000 (unreliable) > [cadb3ec0] [c0007788] do_notify_resume+0x260/0x314 > [cadb3f20] [c000c764] syscall_exit_prepare+0x120/0x184 > [cadb3f30] [c00100b4] ret_from_syscall+0xc/0x28 > --- interrupt: c00 at 0xfe807f8 > NIP: 0fe807f8 LR: 10001060 CTR: c0139378 > REGS: cadb3f40 TRAP: 0c00 Not tainted (5.12.0-rc4-s3k-dev-01553-gb30c310ea220) > MSR: 0000d032 CR: 28000482 XER: 20000000 > > [...] Applied to powerpc/fixes. [1/1] powerpc/signal32: Fix Oops on sigreturn with unmapped VDSO https://git.kernel.org/powerpc/c/acca57217c688c5bbbd5140974533d81e8757cc9 cheers