Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932427AbdC1NVo (ORCPT ); Tue, 28 Mar 2017 09:21:44 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:60138 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932113AbdC1Mk4 (ORCPT ); Tue, 28 Mar 2017 08:40:56 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ard Biesheuvel , Neeraj Upadhyay , Srinivas Ramana , Will Deacon Subject: [PATCH 4.10 090/111] arm64: kaslr: Fix up the kernel image alignment Date: Tue, 28 Mar 2017 14:31:16 +0200 Message-Id: <20170328122919.396357128@linuxfoundation.org> X-Mailer: git-send-email 2.12.1 In-Reply-To: <20170328122915.640228468@linuxfoundation.org> References: <20170328122915.640228468@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3087 Lines: 81 4.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Neeraj Upadhyay commit afd0e5a876703accb95894f23317a13e2c49b523 upstream. If kernel image extends across alignment boundary, existing code increases the KASLR offset by size of kernel image. The offset is masked after resizing. There are cases, where after masking, we may still have kernel image extending across boundary. This eventually results in only 2MB block getting mapped while creating the page tables. This results in data aborts while accessing unmapped regions during second relocation (with kaslr offset) in __primary_switch. To fix this problem, round up the kernel image size, by swapper block size, before adding it for correction. For example consider below case, where kernel image still crosses 1GB alignment boundary, after masking the offset, which is fixed by rounding up kernel image size. SWAPPER_TABLE_SHIFT = 30 Swapper using section maps with section size 2MB. CONFIG_PGTABLE_LEVELS = 3 VA_BITS = 39 _text : 0xffffff8008080000 _end : 0xffffff800aa1b000 offset : 0x1f35600000 mask = ((1UL << (VA_BITS - 2)) - 1) & ~(SZ_2M - 1) (_text + offset) >> SWAPPER_TABLE_SHIFT = 0x3fffffe7c (_end + offset) >> SWAPPER_TABLE_SHIFT = 0x3fffffe7d offset after existing correction (before mask) = 0x1f37f9b000 (_text + offset) >> SWAPPER_TABLE_SHIFT = 0x3fffffe7d (_end + offset) >> SWAPPER_TABLE_SHIFT = 0x3fffffe7d offset (after mask) = 0x1f37e00000 (_text + offset) >> SWAPPER_TABLE_SHIFT = 0x3fffffe7c (_end + offset) >> SWAPPER_TABLE_SHIFT = 0x3fffffe7d new offset w/ rounding up = 0x1f38000000 (_text + offset) >> SWAPPER_TABLE_SHIFT = 0x3fffffe7d (_end + offset) >> SWAPPER_TABLE_SHIFT = 0x3fffffe7d Fixes: f80fb3a3d508 ("arm64: add support for kernel ASLR") Reviewed-by: Ard Biesheuvel Signed-off-by: Neeraj Upadhyay Signed-off-by: Srinivas Ramana Signed-off-by: Will Deacon Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/kaslr.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) --- a/arch/arm64/kernel/kaslr.c +++ b/arch/arm64/kernel/kaslr.c @@ -131,11 +131,15 @@ u64 __init kaslr_early_init(u64 dt_phys, /* * The kernel Image should not extend across a 1GB/32MB/512MB alignment * boundary (for 4KB/16KB/64KB granule kernels, respectively). If this - * happens, increase the KASLR offset by the size of the kernel image. + * happens, increase the KASLR offset by the size of the kernel image + * rounded up by SWAPPER_BLOCK_SIZE. */ if ((((u64)_text + offset + modulo_offset) >> SWAPPER_TABLE_SHIFT) != - (((u64)_end + offset + modulo_offset) >> SWAPPER_TABLE_SHIFT)) - offset = (offset + (u64)(_end - _text)) & mask; + (((u64)_end + offset + modulo_offset) >> SWAPPER_TABLE_SHIFT)) { + u64 kimg_sz = _end - _text; + offset = (offset + round_up(kimg_sz, SWAPPER_BLOCK_SIZE)) + & mask; + } if (IS_ENABLED(CONFIG_KASAN)) /*