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204 lines
6.6 KiB
204 lines
6.6 KiB
6 months ago
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Author: Charles Fol <folcharles@gmail.com>
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Date: Thu Mar 28 12:25:38 2024 -0300
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iconv: ISO-2022-CN-EXT: fix out-of-bound writes when writing escape sequence (CVE-2024-2961)
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ISO-2022-CN-EXT uses escape sequences to indicate character set changes
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(as specified by RFC 1922). While the SOdesignation has the expected
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bounds checks, neither SS2designation nor SS3designation have its;
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allowing a write overflow of 1, 2, or 3 bytes with fixed values:
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'$+I', '$+J', '$+K', '$+L', '$+M', or '$*H'.
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Checked on aarch64-linux-gnu.
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Co-authored-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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Tested-by: Carlos O'Donell <carlos@redhat.com>
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diff --git a/iconvdata/Makefile b/iconvdata/Makefile
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index 646e2ccd11478646..c959758a90ed954f 100644
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--- a/iconvdata/Makefile
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+++ b/iconvdata/Makefile
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@@ -75,7 +75,7 @@ ifeq (yes,$(build-shared))
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tests = bug-iconv1 bug-iconv2 tst-loading tst-e2big tst-iconv4 bug-iconv4 \
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tst-iconv6 bug-iconv5 bug-iconv6 tst-iconv7 bug-iconv8 bug-iconv9 \
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bug-iconv10 bug-iconv11 bug-iconv12 bug-iconv13 bug-iconv14 \
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- bug-iconv15
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+ bug-iconv15 tst-iconv-iso-2022-cn-ext
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ifeq ($(have-thread-library),yes)
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tests += bug-iconv3
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endif
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@@ -325,6 +325,8 @@ $(objpfx)bug-iconv14.out: $(addprefix $(objpfx), $(gconv-modules)) \
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$(addprefix $(objpfx),$(modules.so))
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$(objpfx)bug-iconv15.out: $(addprefix $(objpfx), $(gconv-modules)) \
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$(addprefix $(objpfx),$(modules.so))
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+$(objpfx)tst-iconv-iso-2022-cn-ext.out: $(addprefix $(objpfx), $(gconv-modules)) \
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+ $(addprefix $(objpfx),$(modules.so))
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$(objpfx)iconv-test.out: run-iconv-test.sh \
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$(addprefix $(objpfx), $(gconv-modules)) \
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diff --git a/iconvdata/iso-2022-cn-ext.c b/iconvdata/iso-2022-cn-ext.c
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index c21a7187b4d7808e..bd9493c12d95070b 100644
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--- a/iconvdata/iso-2022-cn-ext.c
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+++ b/iconvdata/iso-2022-cn-ext.c
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@@ -575,6 +575,12 @@ DIAG_IGNORE_Os_NEEDS_COMMENT (5, "-Wmaybe-uninitialized");
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{ \
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const char *escseq; \
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\
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+ if (outptr + 4 > outend) \
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+ { \
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+ result = __GCONV_FULL_OUTPUT; \
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+ break; \
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+ } \
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+ \
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assert (used == CNS11643_2_set); /* XXX */ \
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escseq = "*H"; \
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*outptr++ = ESC; \
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@@ -588,6 +594,12 @@ DIAG_IGNORE_Os_NEEDS_COMMENT (5, "-Wmaybe-uninitialized");
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{ \
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const char *escseq; \
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\
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+ if (outptr + 4 > outend) \
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+ { \
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+ result = __GCONV_FULL_OUTPUT; \
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+ break; \
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+ } \
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+ \
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assert ((used >> 5) >= 3 && (used >> 5) <= 7); \
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escseq = "+I+J+K+L+M" + ((used >> 5) - 3) * 2; \
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*outptr++ = ESC; \
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diff --git a/iconvdata/tst-iconv-iso-2022-cn-ext.c b/iconvdata/tst-iconv-iso-2022-cn-ext.c
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new file mode 100644
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index 0000000000000000..96a8765fd5369681
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--- /dev/null
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+++ b/iconvdata/tst-iconv-iso-2022-cn-ext.c
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@@ -0,0 +1,128 @@
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+/* Verify ISO-2022-CN-EXT does not write out of the bounds.
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+ Copyright (C) 2024 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+#include <stdio.h>
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+#include <string.h>
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+
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+#include <errno.h>
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+#include <iconv.h>
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+#include <sys/mman.h>
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+
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+#include <support/xunistd.h>
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+#include <support/check.h>
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+#include <support/support.h>
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+
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+/* The test sets up a two memory page buffer with the second page marked
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+ PROT_NONE to trigger a fault if the conversion writes beyond the exact
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+ expected amount. Then we carry out various conversions and precisely
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+ place the start of the output buffer in order to trigger a SIGSEGV if the
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+ process writes anywhere between 1 and page sized bytes more (only one
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+ PROT_NONE page is setup as a canary) than expected. These tests exercise
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+ all three of the cases in ISO-2022-CN-EXT where the converter must switch
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+ character sets and may run out of buffer space while doing the
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+ operation. */
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+
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+static int
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+do_test (void)
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+{
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+ iconv_t cd = iconv_open ("ISO-2022-CN-EXT", "UTF-8");
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+ TEST_VERIFY_EXIT (cd != (iconv_t) -1);
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+
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+ char *ntf;
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+ size_t ntfsize;
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+ char *outbufbase;
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+ {
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+ int pgz = getpagesize ();
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+ TEST_VERIFY_EXIT (pgz > 0);
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+ ntfsize = 2 * pgz;
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+
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+ ntf = xmmap (NULL, ntfsize, PROT_READ | PROT_WRITE, MAP_PRIVATE
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+ | MAP_ANONYMOUS, -1);
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+ xmprotect (ntf + pgz, pgz, PROT_NONE);
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+
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+ outbufbase = ntf + pgz;
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+ }
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+
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+ /* Check if SOdesignation escape sequence does not trigger an OOB write. */
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+ {
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+ char inbuf[] = "\xe4\xba\xa4\xe6\x8d\xa2";
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+
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+ for (int i = 0; i < 9; i++)
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+ {
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+ char *inp = inbuf;
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+ size_t inleft = sizeof (inbuf) - 1;
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+
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+ char *outp = outbufbase - i;
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+ size_t outleft = i;
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+
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+ TEST_VERIFY_EXIT (iconv (cd, &inp, &inleft, &outp, &outleft)
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+ == (size_t) -1);
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+ TEST_COMPARE (errno, E2BIG);
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+
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+ TEST_VERIFY_EXIT (iconv (cd, NULL, NULL, NULL, NULL) == 0);
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+ }
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+ }
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+
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+ /* Same as before for SS2designation. */
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+ {
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+ char inbuf[] = "㴽 \xe3\xb4\xbd";
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+
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+ for (int i = 0; i < 14; i++)
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+ {
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+ char *inp = inbuf;
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+ size_t inleft = sizeof (inbuf) - 1;
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+
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+ char *outp = outbufbase - i;
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+ size_t outleft = i;
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+
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+ TEST_VERIFY_EXIT (iconv (cd, &inp, &inleft, &outp, &outleft)
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+ == (size_t) -1);
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+ TEST_COMPARE (errno, E2BIG);
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+
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+ TEST_VERIFY_EXIT (iconv (cd, NULL, NULL, NULL, NULL) == 0);
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+ }
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+ }
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+
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+ /* Same as before for SS3designation. */
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+ {
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+ char inbuf[] = "劄 \xe5\x8a\x84";
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+
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+ for (int i = 0; i < 14; i++)
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+ {
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+ char *inp = inbuf;
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+ size_t inleft = sizeof (inbuf) - 1;
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+
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+ char *outp = outbufbase - i;
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+ size_t outleft = i;
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+
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+ TEST_VERIFY_EXIT (iconv (cd, &inp, &inleft, &outp, &outleft)
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+ == (size_t) -1);
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+ TEST_COMPARE (errno, E2BIG);
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+
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+ TEST_VERIFY_EXIT (iconv (cd, NULL, NULL, NULL, NULL) == 0);
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+ }
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+ }
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+
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+ TEST_VERIFY_EXIT (iconv_close (cd) != -1);
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+
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+ xmunmap (ntf, ntfsize);
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+
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+ return 0;
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+}
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+
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+#include <support/test-driver.c>
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