From a3c2e4e20b08e546201c267fa47aa2b96b507eae Mon Sep 17 00:00:00 2001 From: "Dmitry V. Levin" Date: Sat, 24 Dec 2016 17:35:40 +0000 Subject: [PATCH] printstr_ex: fix decoding of non-NUL-terminated strings when len == -1 Do not treat len == -1 in any special way. All users who need the string to be handled as a NUL-terminated string set QUOTE_0_TERMINATED bit in user_style flags already. * util.c (printstr_ex): Remove (len == -1) check. * tests/printstr.c: New file. * tests/printstr.test: New test. * tests/.gitignore: Add printstr. * tests/Makefile.am (check_PROGRAMS): Likewise. (DECODER_TESTS): Add printstr.test. --- tests/.gitignore | 1 + tests/Makefile.am | 2 ++ tests/printstr.c | 69 +++++++++++++++++++++++++++++++++++++++++++++ tests/printstr.test | 6 ++++ util.c | 25 ++++++---------- 5 files changed, 87 insertions(+), 16 deletions(-) create mode 100644 tests/printstr.c create mode 100755 tests/printstr.test diff --git a/tests/.gitignore b/tests/.gitignore index 3b04590a..2f2c5d9e 100644 --- a/tests/.gitignore +++ b/tests/.gitignore @@ -223,6 +223,7 @@ preadv preadv-pwritev preadv2-pwritev2 print_maxfd +printstr prlimit64 process_vm_readv process_vm_writev diff --git a/tests/Makefile.am b/tests/Makefile.am index 7a8b411c..793a0dc9 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -283,6 +283,7 @@ check_PROGRAMS = \ preadv-pwritev \ preadv2-pwritev2 \ print_maxfd \ + printstr \ prlimit64 \ process_vm_readv \ process_vm_writev \ @@ -667,6 +668,7 @@ DECODER_TESTS = \ preadv-pwritev.test \ preadv2-pwritev2.test \ preadv.test \ + printstr.test \ prlimit64.test \ process_vm_readv.test \ process_vm_writev.test \ diff --git a/tests/printstr.c b/tests/printstr.c new file mode 100644 index 00000000..330234f1 --- /dev/null +++ b/tests/printstr.c @@ -0,0 +1,69 @@ +/* + * Check decoding of non-NUL-terminated strings when len == -1. + * + * Copyright (c) 2016 Dmitry V. Levin + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "tests.h" + +#include +#include +#include +#include + +#define DEFAULT_STRLEN 32 + +int +main(void) +{ + char *const buf = tail_alloc(DEFAULT_STRLEN + 1); + const struct iovec io = { + .iov_base = buf, + .iov_len = -1 + }; + int rc; + + buf[0] = 0; + + tprintf("%s", ""); + + memset(buf + 1, 'X', DEFAULT_STRLEN); + buf[DEFAULT_STRLEN - 1] = 0; + + rc = writev(-1, &io, 1); + tprintf("writev(-1, [{iov_base=\"\\0%*s\\0\"..., iov_len=%lu}], 1)" + " = %s\n", DEFAULT_STRLEN - 2, buf + 1, -1UL, sprintrc(rc)); + + buf[DEFAULT_STRLEN - 1] = 'X'; + buf[DEFAULT_STRLEN] = 0; + + rc = writev(-1, &io, 1); + tprintf("writev(-1, [{iov_base=\"\\0%*s\"..., iov_len=%lu}], 1)" + " = %s\n", DEFAULT_STRLEN - 1, buf + 1, -1UL, sprintrc(rc)); + + tprintf("+++ exited with 0 +++\n"); + return 0; +} diff --git a/tests/printstr.test b/tests/printstr.test new file mode 100755 index 00000000..5f164eb7 --- /dev/null +++ b/tests/printstr.test @@ -0,0 +1,6 @@ +#!/bin/sh + +# Check decoding of non-NUL-terminated strings when len == -1. +. "${srcdir=.}/init.sh" + +run_strace_match_diff -e trace=writev diff --git a/util.c b/util.c index bfc4134e..7dc6863e 100644 --- a/util.c +++ b/util.c @@ -850,12 +850,11 @@ printpath(struct tcb *const tcp, const kernel_ureg_t addr) /* * Print string specified by address `addr' and length `len'. - * If `len' == -1, set QUOTE_0_TERMINATED bit in `user_style'. * If `user_style' has QUOTE_0_TERMINATED bit set, treat the string * as a NUL-terminated string. * Pass `user_style' on to `string_quote'. * Append `...' to the output if either the string length exceeds `max_strlen', - * or `len' != -1 and the string length exceeds `len'. + * or QUOTE_0_TERMINATED bit is set and the string length exceeds `len'. */ void printstr_ex(struct tcb *const tcp, const kernel_ureg_t addr, const long len, @@ -882,22 +881,16 @@ printstr_ex(struct tcb *const tcp, const kernel_ureg_t addr, const long len, outstr = xmalloc(outstr_size); } + /* Fetch one byte more because string_quote may look one byte ahead. */ size = max_strlen + 1; - if (len == -1) { - /* - * Treat as a NUL-terminated string: fetch one byte more - * because string_quote may look one byte ahead. - */ - style |= QUOTE_0_TERMINATED; + + if (size > (unsigned long) len) + size = (unsigned long) len; + if (style & QUOTE_0_TERMINATED) rc = umovestr(tcp, addr, size, str); - } else { - if (size > (unsigned long) len) - size = (unsigned long) len; - if (style & QUOTE_0_TERMINATED) - rc = umovestr(tcp, addr, size, str); - else - rc = umoven(tcp, addr, size, str); - } + else + rc = umoven(tcp, addr, size, str); + if (rc < 0) { printaddr(addr); return; -- 2.40.0