From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-11.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI,T_DKIMWL_WL_MED,USER_IN_DEF_DKIM_WL shortcircuit=no autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 609991F404 for ; Wed, 29 Aug 2018 20:59:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728795AbeH3A5l (ORCPT ); Wed, 29 Aug 2018 20:57:41 -0400 Received: from mail-yw1-f73.google.com ([209.85.161.73]:48068 "EHLO mail-yw1-f73.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727595AbeH3A5l (ORCPT ); Wed, 29 Aug 2018 20:57:41 -0400 Received: by mail-yw1-f73.google.com with SMTP id p8-v6so3142963ywl.14 for ; Wed, 29 Aug 2018 13:59:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=/rJ8A7SwSY/CbKyH1cYYfzeL+g0/ZWoCx88QvHQeZMs=; b=WkRatqRSkSGQ0E5RUXbdzRsBPCZKHKn3BXToY5tK6cQJB+1E713/+eYAeZ8NzLNIx1 Ly3saIHtJjYqXSfwnVesETg4T1yMwOkotE1Ghpogzgcsr1Gov3oz9nt2uFWS419cdh1m v6JX4KkBssPZ8kXxp/6ACbSNECNCJ+pAE0hgdKuySOPj4DPeQ2SSeuC5k09jh+MWzpZF 4lGphbAISj69ubZ1csZXqMyuIt0otjT6SCyJBJoPj5fVb/y2iwk5drcwvkb6D3+JoWOJ o0pMw8E6vss/uZ7xcAeyJaeMuwjb8G4TL2w9DmGODmJ+7DZVPakkdyTxM82Kc3NLizE+ NHSA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=/rJ8A7SwSY/CbKyH1cYYfzeL+g0/ZWoCx88QvHQeZMs=; b=Xsa0KzyZ5KJUFmbSC/vq2sNbJlF+DEA1hNad4IqOoOMoXzefrF18s5joT57zuuRdJ9 vVFue5MPGTFRNI66sPicP77/BxH2fv2LuSsdcRrqnxS2d5RgVwUdR+7CHdYXSnxIVJ1f CtavFMR8WHCh2YP5rWm6vPXWEmXtSJ26+TiVzjUpkoDBHJX7vyF5MAiYz4wrG70e+VGT U1cwcczbo9hUTk/uOF2XQS801WWRRM4tuNV/Knu1mXvxqbv+ZDMLZmnQbTT2SpB191WF b9+pYcQiBdRNYTvJO6ZJoJbA5jqv2vAomuI9PJ8ARChjk+rFpUhw1VatZZebC6stGBjO M93A== X-Gm-Message-State: APzg51BCkXZGFLROG6p8tuMz0lTTMfB73uFkIj98WZOqL3eGwVkhfPDM khbU5PY5iVevO72ZZW86jLTBhet/IFgIdo4GUIHaPmUdPZeqBPvRhmPgOKQOtCCOUj6K6sgeG81 W/tIFz+03Ia+ldySoed3MtFy1RY8yreEVs4aRq5OMWsDiUsUkfYa6xIA= X-Google-Smtp-Source: ANB0VdbNyg3loqJJet3c+DdMrNZXMo4vCrq4jPX06mOyxlceTf8NFaBCWeyae9HQJDFmqOOKVL4i/Gn6uw== X-Received: by 2002:a81:7d83:: with SMTP id y125-v6mr2540877ywc.51.1535576341869; Wed, 29 Aug 2018 13:59:01 -0700 (PDT) Date: Wed, 29 Aug 2018 22:58:55 +0200 Message-Id: <20180829205857.77340-1-jannh@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.19.0.rc0.228.g281dcd1b4d0-goog Subject: [PATCH 1/3] patch-delta: fix oob read From: Jann Horn To: git@vger.kernel.org, jannh@google.com Cc: gitster@pobox.com, "=?UTF-8?q?Nguy=E1=BB=85n=20Th=C3=A1i=20Ng=E1=BB=8Dc=20Duy?=" , Johannes Schindelin , Jeff King , Nicolas Pitre Content-Type: text/plain; charset="UTF-8" Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org If `cmd` is in the range [0x01,0x7f] and `cmd > top-data`, the `memcpy(out, data, cmd)` can copy out-of-bounds data from after `delta_buf` into `dst_buf`. This is not an exploitable bug because triggering the bug increments the `data` pointer beyond `top`, causing the `data != top` sanity check after the loop to trigger and discard the destination buffer - which means that the result of the out-of-bounds read is never used for anything. Also, directly jump into the error handler instead of just breaking out of the loop - otherwise, data corruption would be silently ignored if the delta buffer ends with a command and the destination buffer is already full. Signed-off-by: Jann Horn --- patch-delta.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/patch-delta.c b/patch-delta.c index 56e0a5ede..283fb4b75 100644 --- a/patch-delta.c +++ b/patch-delta.c @@ -51,13 +51,13 @@ void *patch_delta(const void *src_buf, unsigned long src_size, if (unsigned_add_overflows(cp_off, cp_size) || cp_off + cp_size > src_size || cp_size > size) - break; + goto bad_length; memcpy(out, (char *) src_buf + cp_off, cp_size); out += cp_size; size -= cp_size; } else if (cmd) { - if (cmd > size) - break; + if (cmd > size || cmd > top - data) + goto bad_length; memcpy(out, data, cmd); out += cmd; data += cmd; @@ -75,6 +75,7 @@ void *patch_delta(const void *src_buf, unsigned long src_size, /* sanity check */ if (data != top || size != 0) { + bad_length: error("delta replay has gone wild"); bad: free(dst_buf); -- 2.19.0.rc0.228.g281dcd1b4d0-goog