From patchwork Fri Aug 25 16:43:41 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: George Dunlap X-Patchwork-Id: 9922513 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id AE1696022E for ; Fri, 25 Aug 2017 16:48:41 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9DD46281D2 for ; Fri, 25 Aug 2017 16:48:41 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 92B76283CB; Fri, 25 Aug 2017 16:48:41 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id DA4F0281D2 for ; Fri, 25 Aug 2017 16:48:40 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dlHkh-00067S-Ei; Fri, 25 Aug 2017 16:46:35 +0000 Received: from mail6.bemta6.messagelabs.com ([193.109.254.103]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dlHkg-00066o-9l for xen-devel@lists.xenproject.org; Fri, 25 Aug 2017 16:46:34 +0000 Received: from [85.158.143.35] by server-2.bemta-6.messagelabs.com id 1A/25-11743-96450A95; Fri, 25 Aug 2017 16:46:33 +0000 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFupnkeJIrShJLcpLzFFi42JxWrohUjcjZEG kwZ1XVhbft0xmcmD0OPzhCksAYxRrZl5SfkUCa8bLz7+YCzaFVuz7coq5gfGKXRcjJ4eEgL9E 6/efbCA2m4CexLzjX1m6GDk4RARUJG7vNehi5OJgFtjPKNH79QdYjbBAjMTN5a9ZQWwWAVWJj slTmEFsXgE7ibUzNrNBzJSXOPfgNjPIHE6g+K6TXCCmkICtxIszeiAVQkCdix8cZYfoFJQ4Of MJC4jNLCAhcfDFC+YJjLyzkKRmIUktYGRaxahRnFpUllqka2ihl1SUmZ5RkpuYmaNraGCml5t aXJyYnpqTmFSsl5yfu4kRGDgMQLCD8ebGgEOMkhxMSqK81i/nRwrxJeWnVGYkFmfEF5XmpBYf YpTh4FCS4GUPXhApJFiUmp5akZaZAwxhmLQEB4+SCK8ZSJq3uCAxtzgzHSJ1ilGXY87vHV+Yh Fjy8vNSpcR5eUGKBECKMkrz4EbA4ukSo6yUMC8j0FFCPAWpRbmZJajyrxjFORiVhHk1QKbwZO aVwG16BXQEE9ARk07MATmiJBEhJdXAyJnF/8G7JCrUvktLSD6xq/b/nu4vbktDgrNt7fyC7KK Mqn627S9ZYTPPT/qJu4yRXua995c4VTNOGG7zX/Zhzj35778SZ/NPj3H9mtLA/OPKtnsbUrtN pbVZX4m17queeuTs9SgznoiJG97Im/FOXWLJFzVPyDNmeaa2mvTNePtKnn2bnlYqsRRnJBpqM RcVJwIAqN1xvaICAAA= X-Env-Sender: prvs=4030414b0=George.Dunlap@citrix.com X-Msg-Ref: server-5.tower-21.messagelabs.com!1503679591!71624617!1 X-Originating-IP: [66.165.176.89] X-SpamReason: No, hits=0.0 required=7.0 tests=sa_preprocessor: VHJ1c3RlZCBJUDogNjYuMTY1LjE3Ni44OSA9PiAyMDMwMDc=\n, received_headers: No Received headers X-StarScan-Received: X-StarScan-Version: 9.4.45; banners=-,-,- X-VirusChecked: Checked Received: (qmail 5773 invoked from network); 25 Aug 2017 16:46:32 -0000 Received: from smtp.citrix.com (HELO SMTP.CITRIX.COM) (66.165.176.89) by server-5.tower-21.messagelabs.com with RC4-SHA encrypted SMTP; 25 Aug 2017 16:46:32 -0000 X-IronPort-AV: E=Sophos;i="5.41,426,1498521600"; d="scan'208";a="436909613" From: George Dunlap To: Date: Fri, 25 Aug 2017 17:43:41 +0100 Message-ID: <20170825164343.29015-12-george.dunlap@citrix.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170825164343.29015-1-george.dunlap@citrix.com> References: <20170825164343.29015-1-george.dunlap@citrix.com> MIME-Version: 1.0 Cc: Ian Jackson , Wei Liu , George Dunlap , Jan Beulich , Andrew Cooper Subject: [Xen-devel] [PATCH 12/14] fuzz/x86_emulate: Add --rerun option to try to track down instability X-BeenThere: xen-devel@lists.xen.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" X-Virus-Scanned: ClamAV using ClamSMTP Current stability numbers are not 100%. In order to help track this down, add a --rerun option which will run the same input twice, resetting the state in between each run, and comparing the state afterwards. If the state differs, call abort(). This allows AFL to help the process of tracking down what state is not being reset properly between runs by proving testcases that demonstrate the behavior. To do this: - Move ctxt into struct fuzz-state to simplify handling - Rather than copying the data into input, treat the data handed as immutable and point each "copy" to it - Factor out various steps (setting up fuzz state, running an individual test) so that they can be efficiently run either once or twice (as necessary) - Compare the states afterwards, printing what's different and calling abort() if anything is found. Signed-off-by: George Dunlap --- CC: Ian Jackson CC: Wei Liu CC: Andrew Cooper CC: Jan Beulich --- tools/fuzz/x86_instruction_emulator/afl-harness.c | 9 +- tools/fuzz/x86_instruction_emulator/fuzz-emul.c | 182 ++++++++++++++++++---- 2 files changed, 159 insertions(+), 32 deletions(-) diff --git a/tools/fuzz/x86_instruction_emulator/afl-harness.c b/tools/fuzz/x86_instruction_emulator/afl-harness.c index 12b3765dcc..86c1241784 100644 --- a/tools/fuzz/x86_instruction_emulator/afl-harness.c +++ b/tools/fuzz/x86_instruction_emulator/afl-harness.c @@ -14,6 +14,7 @@ extern unsigned int fuzz_minimal_input_size(void); static uint8_t input[INPUT_SIZE]; extern bool opt_compact; +extern bool opt_rerun; int main(int argc, char **argv) { @@ -32,10 +33,12 @@ int main(int argc, char **argv) enum { OPT_MIN_SIZE, OPT_COMPACT, + OPT_RERUN, }; static const struct option lopts[] = { { "min-input-size", no_argument, NULL, OPT_MIN_SIZE }, { "compact", required_argument, NULL, OPT_COMPACT }, + { "rerun", no_argument, NULL, OPT_RERUN }, { 0, 0, 0, 0 } }; int c = getopt_long_only(argc, argv, "", lopts, NULL); @@ -54,8 +57,12 @@ int main(int argc, char **argv) opt_compact = atoi(optarg); break; + case OPT_RERUN: + opt_rerun = true; + break; + case '?': - printf("Usage: %s [--compact=0|1] $FILE [$FILE...] | [--min-input-size]\n", argv[0]); + printf("Usage: %s [--compact=0|1] [--rerun] $FILE [$FILE...] | [--min-input-size]\n", argv[0]); exit(-1); break; diff --git a/tools/fuzz/x86_instruction_emulator/fuzz-emul.c b/tools/fuzz/x86_instruction_emulator/fuzz-emul.c index 48b02f2bf6..1d0293e990 100644 --- a/tools/fuzz/x86_instruction_emulator/fuzz-emul.c +++ b/tools/fuzz/x86_instruction_emulator/fuzz-emul.c @@ -40,7 +40,7 @@ struct fuzz_state struct cpu_user_regs regs; /* Fuzzer's input data. */ - struct fuzz_corpus *corpus; + const struct fuzz_corpus *corpus; /* Real amount of data backing corpus->data[]. */ size_t data_num; @@ -50,6 +50,7 @@ struct fuzz_state /* Emulation ops, some of which are disabled based on corpus->options. */ struct x86_emulate_ops ops; + struct x86_emulate_ctxt ctxt; }; #define DATA_OFFSET offsetof(struct fuzz_state, corpus) @@ -496,6 +497,12 @@ static int fuzz_read_msr( const struct fuzz_state *s = ctxt->data; unsigned int idx; + /* + * NB at the moment dump_state() relies on the fact that this + * cannot fail. If we add in fuzzed failures we'll have to handle + * that differently. + */ + switch ( reg ) { case MSR_TSC_AUX: @@ -616,6 +623,7 @@ static void dump_state(struct x86_emulate_ctxt *ctxt) printf(" rip: %"PRIx64"\n", regs->rip); + /* read_msr() never fails at the moment */ fuzz_read_msr(MSR_EFER, &val, ctxt); printf("EFER: %"PRIx64"\n", val); } @@ -660,7 +668,10 @@ static void setup_state(struct x86_emulate_ctxt *ctxt) { /* Fuzz all of the state in one go */ if (!dread(s, s, DATA_OFFSET)) + { + printf("Input size too small\n"); exit(-1); + } return; } @@ -789,9 +800,8 @@ enum { printf("Disabling hook "#h"\n"); \ } -static void disable_hooks(struct x86_emulate_ctxt *ctxt) +static void disable_hooks(struct fuzz_state *s) { - struct fuzz_state *s = ctxt->data; unsigned long bitmap = s->options; /* See also sanitize_input, some hooks can't be disabled. */ @@ -839,7 +849,7 @@ static void disable_hooks(struct x86_emulate_ctxt *ctxt) * - ...bases to below 1Mb, 16-byte aligned * - ...selectors to (base >> 4) */ -static void sanitize_input(struct x86_emulate_ctxt *ctxt) +static void sanitize_state(struct x86_emulate_ctxt *ctxt) { struct fuzz_state *s = ctxt->data; struct cpu_user_regs *regs = ctxt->regs; @@ -886,21 +896,132 @@ int LLVMFuzzerInitialize(int *argc, char ***argv) return 0; } -int LLVMFuzzerTestOneInput(const uint8_t *data_p, size_t size) +void setup_fuzz_state(struct fuzz_state *state, const uint8_t *data_p, size_t size) { - struct fuzz_state state = { - .ops = all_fuzzer_ops, - }; - struct x86_emulate_ctxt ctxt = { - .data = &state, - .regs = &state.regs, - .addr_size = 8 * sizeof(void *), - .sp_size = 8 * sizeof(void *), - }; + memset(state, 0, sizeof(*state)); + state->corpus = (struct fuzz_corpus *)data_p; + state->data_num = size; +} + +int runtest(struct fuzz_state *state) { int rc; - /* Reset all global state variables */ - memset(&input, 0, sizeof(input)); + struct x86_emulate_ctxt *ctxt = &state->ctxt; + + state->ops = all_fuzzer_ops; + + ctxt->data = state; + ctxt->regs = &state->regs; + ctxt->addr_size = ctxt->sp_size = 8 * sizeof(void *); + + setup_state(ctxt); + + sanitize_state(ctxt); + + disable_hooks(state); + + do { + /* FIXME: Until we actually implement SIGFPE handling properly */ + setup_fpu_exception_handler(); + + set_sizes(ctxt); + dump_state(ctxt); + + rc = x86_emulate(ctxt, &state->ops); + printf("Emulation result: %d\n", rc); + } while ( rc == X86EMUL_OKAY ); + + return 0; +} + +void compare_states(struct fuzz_state state[2]) +{ + // First zero any "internal" pointers + state[0].corpus = state[1].corpus = NULL; + state[0].ctxt.data = state[1].ctxt.data = NULL; + state[0].ctxt.regs = state[1].ctxt.regs = NULL; + + + if ( memcmp(&state[0], &state[1], sizeof(struct fuzz_state)) ) + { + int i; + + printf("State mismatch\n"); + + for ( i=0; i<5; i++) + if (state[0].cr[i] != state[1].cr[i]) + printf("cr[%d]: %lx != %lx\n", + i, state[0].cr[i], state[1].cr[i]); + + for ( i=0; i sizeof(input) ) + if ( size > sizeof(struct fuzz_corpus) ) { printf("Input too large\n"); return 1; @@ -916,25 +1037,24 @@ int LLVMFuzzerTestOneInput(const uint8_t *data_p, size_t size) memcpy(&input, data_p, size); - state.corpus = &input; - state.data_num = size; - - setup_state(&ctxt); + setup_fuzz_state(&state[0], data_p, size); + + if ( opt_rerun ) + printf("||| INITIAL RUN |||\n"); + + runtest(&state[0]); - sanitize_input(&ctxt); + if ( !opt_rerun ) + return 0; - disable_hooks(&ctxt); + /* Reset all global state variables again */ + setup_fuzz_state(&state[1], data_p, size); - do { - /* FIXME: Until we actually implement SIGFPE handling properly */ - setup_fpu_exception_handler(); + printf("||| SECOND RUN |||\n"); - set_sizes(&ctxt); - dump_state(&ctxt); + runtest(&state[1]); - rc = x86_emulate(&ctxt, &state.ops); - printf("Emulation result: %d\n", rc); - } while ( rc == X86EMUL_OKAY ); + compare_states(state); return 0; }