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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
(as specified by RFC 1922).  While the SOdesignation has the expected
bounds checks, neither SS2designation nor SS3designation have its;
allowing a write overflow of 1, 2, or 3 bytes with fixed values:
'$+I', '$+J', '$+K', '$+L', '$+M', or '$*H'.

Checked on aarch64-linux-gnu.

Co-authored-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Charles Fol 2024-03-28 12:25:38 -03:00 committed by Adhemerval Zanella
parent 59974938fe
commit f9dc609e06
3 changed files with 144 additions and 1 deletions
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5
iconvdata/Makefile
View File

@ -75,7 +75,8 @@ ifeq (yes,$(build-shared))
tests = bug-iconv1 bug-iconv2 tst-loading tst-e2big tst-iconv4 bug-iconv4 \
tst-iconv6 bug-iconv5 bug-iconv6 tst-iconv7 bug-iconv8 bug-iconv9 \
bug-iconv10 bug-iconv11 bug-iconv12 tst-iconv-big5-hkscs-to-2ucs4 \
bug-iconv13 bug-iconv14 bug-iconv15
bug-iconv13 bug-iconv14 bug-iconv15 \
tst-iconv-iso-2022-cn-ext
ifeq ($(have-thread-library),yes)
tests += bug-iconv3
endif
@ -330,6 +331,8 @@ $(objpfx)bug-iconv14.out: $(addprefix $(objpfx), $(gconv-modules)) \
$(addprefix $(objpfx),$(modules.so))
$(objpfx)bug-iconv15.out: $(addprefix $(objpfx), $(gconv-modules)) \
$(addprefix $(objpfx),$(modules.so))
$(objpfx)tst-iconv-iso-2022-cn-ext.out: $(addprefix $(objpfx), $(gconv-modules)) \
$(addprefix $(objpfx),$(modules.so))
$(objpfx)iconv-test.out: run-iconv-test.sh \
$(addprefix $(objpfx), $(gconv-modules)) \

12
iconvdata/iso-2022-cn-ext.c
View File

@ -574,6 +574,12 @@ DIAG_IGNORE_Os_NEEDS_COMMENT (5, "-Wmaybe-uninitialized");
{ \
const char *escseq; \
\
if (outptr + 4 > outend) \
{ \
result = __GCONV_FULL_OUTPUT; \
break; \
} \
\
assert (used == CNS11643_2_set); /* XXX */ \
escseq = "*H"; \
*outptr++ = ESC; \
@ -587,6 +593,12 @@ DIAG_IGNORE_Os_NEEDS_COMMENT (5, "-Wmaybe-uninitialized");
{ \
const char *escseq; \
\
if (outptr + 4 > outend) \
{ \
result = __GCONV_FULL_OUTPUT; \
break; \
} \
\
assert ((used >> 5) >= 3 && (used >> 5) <= 7); \
escseq = "+I+J+K+L+M" + ((used >> 5) - 3) * 2; \
*outptr++ = ESC; \

128
iconvdata/tst-iconv-iso-2022-cn-ext.c Normal file
View File

@ -0,0 +1,128 @@
/* Verify ISO-2022-CN-EXT does not write out of the bounds.
Copyright (C) 2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <iconv.h>
#include <sys/mman.h>
#include <support/xunistd.h>
#include <support/check.h>
#include <support/support.h>
/* The test sets up a two memory page buffer with the second page marked
PROT_NONE to trigger a fault if the conversion writes beyond the exact
expected amount. Then we carry out various conversions and precisely
place the start of the output buffer in order to trigger a SIGSEGV if the
process writes anywhere between 1 and page sized bytes more (only one
PROT_NONE page is setup as a canary) than expected. These tests exercise
all three of the cases in ISO-2022-CN-EXT where the converter must switch
character sets and may run out of buffer space while doing the
operation. */
static int
do_test (void)
{
iconv_t cd = iconv_open ("ISO-2022-CN-EXT", "UTF-8");
TEST_VERIFY_EXIT (cd != (iconv_t) -1);
char *ntf;
size_t ntfsize;
char *outbufbase;
{
int pgz = getpagesize ();
TEST_VERIFY_EXIT (pgz > 0);
ntfsize = 2 * pgz;
ntf = xmmap (NULL, ntfsize, PROT_READ | PROT_WRITE, MAP_PRIVATE
| MAP_ANONYMOUS, -1);
xmprotect (ntf + pgz, pgz, PROT_NONE);
outbufbase = ntf + pgz;
}
/* Check if SOdesignation escape sequence does not trigger an OOB write. */
{
char inbuf[] = "\xe4\xba\xa4\xe6\x8d\xa2";
for (int i = 0; i < 9; i++)
{
char *inp = inbuf;
size_t inleft = sizeof (inbuf) - 1;
char *outp = outbufbase - i;
size_t outleft = i;
TEST_VERIFY_EXIT (iconv (cd, &inp, &inleft, &outp, &outleft)
== (size_t) -1);
TEST_COMPARE (errno, E2BIG);
TEST_VERIFY_EXIT (iconv (cd, NULL, NULL, NULL, NULL) == 0);
}
}
/* Same as before for SS2designation. */
{
char inbuf[] = "㴽 \xe3\xb4\xbd";
for (int i = 0; i < 14; i++)
{
char *inp = inbuf;
size_t inleft = sizeof (inbuf) - 1;
char *outp = outbufbase - i;
size_t outleft = i;
TEST_VERIFY_EXIT (iconv (cd, &inp, &inleft, &outp, &outleft)
== (size_t) -1);
TEST_COMPARE (errno, E2BIG);
TEST_VERIFY_EXIT (iconv (cd, NULL, NULL, NULL, NULL) == 0);
}
}
/* Same as before for SS3designation. */
{
char inbuf[] = "劄 \xe5\x8a\x84";
for (int i = 0; i < 14; i++)
{
char *inp = inbuf;
size_t inleft = sizeof (inbuf) - 1;
char *outp = outbufbase - i;
size_t outleft = i;
TEST_VERIFY_EXIT (iconv (cd, &inp, &inleft, &outp, &outleft)
== (size_t) -1);
TEST_COMPARE (errno, E2BIG);
TEST_VERIFY_EXIT (iconv (cd, NULL, NULL, NULL, NULL) == 0);
}
}
TEST_VERIFY_EXIT (iconv_close (cd) != -1);
xmunmap (ntf, ntfsize);
return 0;
}
#include <support/test-driver.c>