From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E0237C3A5A8 for ; Wed, 4 Sep 2019 15:59:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B593022DBF for ; Wed, 4 Sep 2019 15:59:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567612747; bh=tIOyhS6VF6IaTHZxXUaqI8fByJAKFcQIdfAgqKw19ic=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=HdqTLlA5i9Yut4pGbAOFoeNfxnW1UUhWxhK9fVvVoLnwZjv+ofrkbd5jJbHILGp8x AvsIre72G0JmcPH/nzeaFn6FDAXbyqonauRe9DT7S9f8hAW7YVEhsFSreTBzjKFttO uSqvNzWf+Budjs96LhN/c0+JYCPmt12ORyhd2bVc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732250AbfIDP7G (ORCPT ); Wed, 4 Sep 2019 11:59:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:33364 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731514AbfIDP7F (ORCPT ); Wed, 4 Sep 2019 11:59:05 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D5A4520820; Wed, 4 Sep 2019 15:59:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567612744; bh=tIOyhS6VF6IaTHZxXUaqI8fByJAKFcQIdfAgqKw19ic=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Smn81ya7D1GfbqPi/G4kC7ez/9sjys13gDaWYvtZPfpoMkc6H2tJjEIo1XrGimdlo 5QUmJDoKQal4Rtj4xeO8t6Y6pMn+V7z44JBYs74O5xmm5jkf3PwKbKZkxpChXpYoow y2ZXjo1B4pAo1YM/bwX4WZOC8+cZsF+n987cyi0k= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Marc Zyngier , Masami Hiramatsu , Arnaldo Carvalho de Melo , Peter Zijlstra , Will Deacon , Catalin Marinas , Sasha Levin Subject: [PATCH AUTOSEL 5.2 56/94] kallsyms: Don't let kallsyms_lookup_size_offset() fail on retrieving the first symbol Date: Wed, 4 Sep 2019 11:57:01 -0400 Message-Id: <20190904155739.2816-56-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190904155739.2816-1-sashal@kernel.org> References: <20190904155739.2816-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Marc Zyngier [ Upstream commit 2a1a3fa0f29270583f0e6e3100d609e09697add1 ] An arm64 kernel configured with CONFIG_KPROBES=y CONFIG_KALLSYMS=y # CONFIG_KALLSYMS_ALL is not set CONFIG_KALLSYMS_BASE_RELATIVE=y reports the following kprobe failure: [ 0.032677] kprobes: failed to populate blacklist: -22 [ 0.033376] Please take care of using kprobes. It appears that kprobe fails to retrieve the symbol at address 0xffff000010081000, despite this symbol being in System.map: ffff000010081000 T __exception_text_start This symbol is part of the first group of aliases in the kallsyms_offsets array (symbol names generated using ugly hacks in scripts/kallsyms.c): kallsyms_offsets: .long 0x1000 // do_undefinstr .long 0x1000 // efi_header_end .long 0x1000 // _stext .long 0x1000 // __exception_text_start .long 0x12b0 // do_cp15instr Looking at the implementation of get_symbol_pos(), it returns the lowest index for aliasing symbols. In this case, it return 0. But kallsyms_lookup_size_offset() considers 0 as a failure, which is obviously wrong (there is definitely a valid symbol living there). In turn, the kprobe blacklisting stops abruptly, hence the original error. A CONFIG_KALLSYMS_ALL kernel wouldn't fail as there is always some random symbols at the beginning of this array, which are never looked up via kallsyms_lookup_size_offset. Fix it by considering that get_symbol_pos() is always successful (which is consistent with the other uses of this function). Fixes: ffc5089196446 ("[PATCH] Create kallsyms_lookup_size_offset()") Reviewed-by: Masami Hiramatsu Cc: Arnaldo Carvalho de Melo Cc: Peter Zijlstra Cc: Will Deacon Cc: Catalin Marinas Signed-off-by: Marc Zyngier Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- kernel/kallsyms.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index 95a260f9214b9..136ce049c4ad2 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -263,8 +263,10 @@ int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, { char namebuf[KSYM_NAME_LEN]; - if (is_ksym_addr(addr)) - return !!get_symbol_pos(addr, symbolsize, offset); + if (is_ksym_addr(addr)) { + get_symbol_pos(addr, symbolsize, offset); + return 1; + } return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf) || !!__bpf_address_lookup(addr, symbolsize, offset, namebuf); } -- 2.20.1