From patchwork Fri Oct 11 11:30:47 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Tzvetomir Stoyanov (VMware)" X-Patchwork-Id: 11185281 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 125EC76 for ; Fri, 11 Oct 2019 11:30:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E6CB921A4A for ; Fri, 11 Oct 2019 11:30:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="C0qCbfmm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727226AbfJKLaw (ORCPT ); Fri, 11 Oct 2019 07:30:52 -0400 Received: from mail-wr1-f65.google.com ([209.85.221.65]:39245 "EHLO mail-wr1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727541AbfJKLaw (ORCPT ); Fri, 11 Oct 2019 07:30:52 -0400 Received: by mail-wr1-f65.google.com with SMTP id r3so11528381wrj.6 for ; Fri, 11 Oct 2019 04:30:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=yRZQ5nDBjUA0rZ4uVF9Or1nvtD246vYQPcKYHvQfA0A=; b=C0qCbfmm0OSIIVBFg1q+pkfmC6hA2xb9bvDjzybXszlf7ND1ApWcMfOd/HgJCOIU7T 35mZze7iCGCgOdq4b+HAVPG79g17F4dPBEf+OYdlbwJoUzRqHXaqDSS29sX/rQrxIVUj Q5tREfafE3f7FH7FCY2vY6WRPJbyt7ZmCKhaCMnKjALWc6cQUYAMpPsHfRmtI5NIHSxB 5io/WOi/3jvuBMwNmUHEN4fOe5JfMsD15PkqmL9CS/ITZpd8M3KESgRLzH/O/f/iAqTc jk2Anqic4FvSIQP/mBjXIQVBs427oOrh3+p0e1rhR65bCtV0DJ0kZAwBTDFJhKDNliKl 6tCA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=yRZQ5nDBjUA0rZ4uVF9Or1nvtD246vYQPcKYHvQfA0A=; b=HtqvX+xq1sdigbgTotPfnk2wWrzPOUjxk/KsiejmPcGDMS53KswgRV5bWzIdMSguXC uPsaC/eRm3Rp5dXaB3cUlKCa5Hm+qIgT7vs3eD+US4WDUgBEsMa7Rg8uJy6M+yrMRtkI my5X0UeacB1JVQM2ZvJ8NrvcNgr3qW+JhbQg65v/wn9FdTwfA2eP6S/aaeTfVp326pZB SlUzlTAZxWVeNm8RnM70PLCX4PUwdb0K/Q0TDpQ1mRkFYoNkJVeDayaRZnSGuYTTZySp FfzGX4haBV6VNn3uywuRnVrbBQOU1gRTVa9woKQ1F2Fz9GT+OpF9lW0dcQLeV2GZ6EJM VTdw== X-Gm-Message-State: APjAAAUHsFHBM6Z3+NhsZC5/qu/aHydap5pysnoOROGE31p3OKUo/zHe C/RU8Z0CfZmMgAlpbOwvvqwRCNQ3 X-Google-Smtp-Source: APXvYqy9rK1n9940dySvUPRg/y5bjAcINejJOjHvXdmE/mM/fmNP5LOi2C7zW1nEC6e/IoXUS0laag== X-Received: by 2002:a05:6000:1190:: with SMTP id g16mr5197173wrx.133.1570793450211; Fri, 11 Oct 2019 04:30:50 -0700 (PDT) Received: from oberon.eng.vmware.com ([146.247.46.5]) by smtp.gmail.com with ESMTPSA id y1sm2481600wrw.6.2019.10.11.04.30.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Oct 2019 04:30:49 -0700 (PDT) From: "Tzvetomir Stoyanov (VMware)" To: rostedt@goodmis.org Cc: linux-trace-devel@vger.kernel.org Subject: [PATCH 1/3] trace-cmd: Fix segmentation fault in tracecmd_read_at() in specific use case Date: Fri, 11 Oct 2019 14:30:47 +0300 Message-Id: <20191011113047.11089-1-tz.stoyanov@gmail.com> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Sender: linux-trace-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org There is a segmentation fault in update_page_info() when the requested page is not loaded, handle->cpu_data[cpu].page is NULL. The problematic flow starts from tracecmd_read_at() API, when reading offset in the first page (less than 4K), and this page is still not loaded. The problem can be observed randomly - there is a sporadic KernelShark crash when loading a file, browsing and zooming events. https://bugzilla.kernel.org/show_bug.cgi?id=205165 Signed-off-by: Tzvetomir Stoyanov (VMware) --- lib/trace-cmd/trace-input.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c index 60ee2f7..1ae2ab5 100644 --- a/lib/trace-cmd/trace-input.c +++ b/lib/trace-cmd/trace-input.c @@ -1345,7 +1345,8 @@ tracecmd_read_at(struct tracecmd_input *handle, unsigned long long offset, /* check to see if we have this page already */ for (cpu = 0; cpu < handle->cpus; cpu++) { if (handle->cpu_data[cpu].offset == page_offset && - handle->cpu_data[cpu].file_size) + handle->cpu_data[cpu].file_size && + handle->cpu_data[cpu].page) break; }