From 8f5e8b01a1da2a207228f2072c934fa5918554b8 Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Fri, 4 Dec 2015 20:36:28 +0000 Subject: [PATCH] Fix nan functions handling of payload strings (bug 16961, bug 16962). The nan, nanf and nanl functions handle payload strings by doing e.g.: if (tagp[0] != '\0') { char buf[6 + strlen (tagp)]; sprintf (buf, "NAN(%s)", tagp); return strtod (buf, NULL); } This is an unbounded stack allocation based on the length of the argument. Furthermore, if the argument starts with an n-char-sequence followed by ')', that n-char-sequence is wrongly treated as significant for determining the payload of the resulting NaN, when ISO C says the call should be equivalent to strtod ("NAN", NULL), without being affected by that initial n-char-sequence. This patch fixes both those problems by using the __strtod_nan etc. functions recently factored out of strtod etc. for that purpose, with those functions being exported from libc at version GLIBC_PRIVATE. Tested for x86_64, x86, mips64 and powerpc. [BZ #16961] [BZ #16962] * math/s_nan.c (__nan): Use __strtod_nan instead of constructing a string on the stack for strtod. * math/s_nanf.c (__nanf): Use __strtof_nan instead of constructing a string on the stack for strtof. * math/s_nanl.c (__nanl): Use __strtold_nan instead of constructing a string on the stack for strtold. * stdlib/Versions (libc): Add __strtof_nan, __strtod_nan and __strtold_nan to GLIBC_PRIVATE. * math/test-nan-overflow.c: New file. * math/test-nan-payload.c: Likewise. * math/Makefile (tests): Add test-nan-overflow and test-nan-payload. Upstream-Status: Backport CVE: CVE-2015-9761 patch #2 [Yocto # 8980] https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=8f5e8b01a1da2a207228f2072c934fa5918554b8 Signed-off-by: Armin Kuster --- ChangeLog | 17 +++++++ NEWS | 6 +++ math/Makefile | 3 +- math/s_nan.c | 9 +--- math/s_nanf.c | 9 +--- math/s_nanl.c | 9 +--- math/test-nan-overflow.c | 66 +++++++++++++++++++++++++ math/test-nan-payload.c | 122 +++++++++++++++++++++++++++++++++++++++++++++++ stdlib/Versions | 1 + 9 files changed, 217 insertions(+), 25 deletions(-) create mode 100644 math/test-nan-overflow.c create mode 100644 math/test-nan-payload.c Index: git/ChangeLog =================================================================== --- git.orig/ChangeLog +++ git/ChangeLog @@ -1,3 +1,20 @@ +2015-12-04 Joseph Myers + + [BZ #16961] + [BZ #16962] + * math/s_nan.c (__nan): Use __strtod_nan instead of constructing a + string on the stack for strtod. + * math/s_nanf.c (__nanf): Use __strtof_nan instead of constructing + a string on the stack for strtof. + * math/s_nanl.c (__nanl): Use __strtold_nan instead of + constructing a string on the stack for strtold. + * stdlib/Versions (libc): Add __strtof_nan, __strtod_nan and + __strtold_nan to GLIBC_PRIVATE. + * math/test-nan-overflow.c: New file. + * math/test-nan-payload.c: Likewise. + * math/Makefile (tests): Add test-nan-overflow and + test-nan-payload. + 2015-11-24 Joseph Myers * stdlib/strtod_nan.c: New file. Index: git/NEWS =================================================================== --- git.orig/NEWS +++ git/NEWS @@ -7,6 +7,12 @@ using `glibc' in the "product" field. Version 2.21 +Security related changes: + +* The nan, nanf and nanl functions no longer have unbounded stack usage + depending on the length of the string passed as an argument to the + functions. Reported by Joseph Myers. + * The following bugs are resolved with this release: 6652, 10672, 12674, 12847, 12926, 13862, 14132, 14138, 14171, 14498, Index: git/math/s_nan.c =================================================================== --- git.orig/math/s_nan.c +++ git/math/s_nan.c @@ -28,14 +28,7 @@ double __nan (const char *tagp) { - if (tagp[0] != '\0') - { - char buf[6 + strlen (tagp)]; - sprintf (buf, "NAN(%s)", tagp); - return strtod (buf, NULL); - } - - return NAN; + return __strtod_nan (tagp, NULL, 0); } weak_alias (__nan, nan) #ifdef NO_LONG_DOUBLE Index: git/math/s_nanf.c =================================================================== --- git.orig/math/s_nanf.c +++ git/math/s_nanf.c @@ -28,13 +28,6 @@ float __nanf (const char *tagp) { - if (tagp[0] != '\0') - { - char buf[6 + strlen (tagp)]; - sprintf (buf, "NAN(%s)", tagp); - return strtof (buf, NULL); - } - - return NAN; + return __strtof_nan (tagp, NULL, 0); } weak_alias (__nanf, nanf) Index: git/math/s_nanl.c =================================================================== --- git.orig/math/s_nanl.c +++ git/math/s_nanl.c @@ -28,13 +28,6 @@ long double __nanl (const char *tagp) { - if (tagp[0] != '\0') - { - char buf[6 + strlen (tagp)]; - sprintf (buf, "NAN(%s)", tagp); - return strtold (buf, NULL); - } - - return NAN; + return __strtold_nan (tagp, NULL, 0); } weak_alias (__nanl, nanl) Index: git/math/test-nan-overflow.c =================================================================== --- /dev/null +++ git/math/test-nan-overflow.c @@ -0,0 +1,66 @@ +/* Test nan functions stack overflow (bug 16962). + Copyright (C) 2015 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 + . */ + +#include +#include +#include +#include + +#define STACK_LIM 1048576 +#define STRING_SIZE (2 * STACK_LIM) + +static int +do_test (void) +{ + int result = 0; + struct rlimit lim; + getrlimit (RLIMIT_STACK, &lim); + lim.rlim_cur = STACK_LIM; + setrlimit (RLIMIT_STACK, &lim); + char *nanstr = malloc (STRING_SIZE); + if (nanstr == NULL) + { + puts ("malloc failed, cannot test"); + return 77; + } + memset (nanstr, '0', STRING_SIZE - 1); + nanstr[STRING_SIZE - 1] = 0; +#define NAN_TEST(TYPE, FUNC) \ + do \ + { \ + char *volatile p = nanstr; \ + volatile TYPE v = FUNC (p); \ + if (isnan (v)) \ + puts ("PASS: " #FUNC); \ + else \ + { \ + puts ("FAIL: " #FUNC); \ + result = 1; \ + } \ + } \ + while (0) + NAN_TEST (float, nanf); + NAN_TEST (double, nan); +#ifndef NO_LONG_DOUBLE + NAN_TEST (long double, nanl); +#endif + return result; +} + +#define TEST_FUNCTION do_test () +#include "../test-skeleton.c" Index: git/math/test-nan-payload.c =================================================================== --- /dev/null +++ git/math/test-nan-payload.c @@ -0,0 +1,122 @@ +/* Test nan functions payload handling (bug 16961). + Copyright (C) 2015 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 + . */ + +#include +#include +#include +#include +#include + +/* Avoid built-in functions. */ +#define WRAP_NAN(FUNC, STR) \ + ({ const char *volatile wns = (STR); FUNC (wns); }) +#define WRAP_STRTO(FUNC, STR) \ + ({ const char *volatile wss = (STR); FUNC (wss, NULL); }) + +#define CHECK_IS_NAN(TYPE, A) \ + do \ + { \ + if (isnan (A)) \ + puts ("PASS: " #TYPE " " #A); \ + else \ + { \ + puts ("FAIL: " #TYPE " " #A); \ + result = 1; \ + } \ + } \ + while (0) + +#define CHECK_SAME_NAN(TYPE, A, B) \ + do \ + { \ + if (memcmp (&(A), &(B), sizeof (A)) == 0) \ + puts ("PASS: " #TYPE " " #A " = " #B); \ + else \ + { \ + puts ("FAIL: " #TYPE " " #A " = " #B); \ + result = 1; \ + } \ + } \ + while (0) + +#define CHECK_DIFF_NAN(TYPE, A, B) \ + do \ + { \ + if (memcmp (&(A), &(B), sizeof (A)) != 0) \ + puts ("PASS: " #TYPE " " #A " != " #B); \ + else \ + { \ + puts ("FAIL: " #TYPE " " #A " != " #B); \ + result = 1; \ + } \ + } \ + while (0) + +/* Cannot test payloads by memcmp for formats where NaNs have padding + bits. */ +#define CAN_TEST_EQ(MANT_DIG) ((MANT_DIG) != 64 && (MANT_DIG) != 106) + +#define RUN_TESTS(TYPE, SFUNC, FUNC, MANT_DIG) \ + do \ + { \ + TYPE n123 = WRAP_NAN (FUNC, "123"); \ + CHECK_IS_NAN (TYPE, n123); \ + TYPE s123 = WRAP_STRTO (SFUNC, "NAN(123)"); \ + CHECK_IS_NAN (TYPE, s123); \ + TYPE n456 = WRAP_NAN (FUNC, "456"); \ + CHECK_IS_NAN (TYPE, n456); \ + TYPE s456 = WRAP_STRTO (SFUNC, "NAN(456)"); \ + CHECK_IS_NAN (TYPE, s456); \ + TYPE n123x = WRAP_NAN (FUNC, "123)"); \ + CHECK_IS_NAN (TYPE, n123x); \ + TYPE nemp = WRAP_NAN (FUNC, ""); \ + CHECK_IS_NAN (TYPE, nemp); \ + TYPE semp = WRAP_STRTO (SFUNC, "NAN()"); \ + CHECK_IS_NAN (TYPE, semp); \ + TYPE sx = WRAP_STRTO (SFUNC, "NAN"); \ + CHECK_IS_NAN (TYPE, sx); \ + if (CAN_TEST_EQ (MANT_DIG)) \ + CHECK_SAME_NAN (TYPE, n123, s123); \ + if (CAN_TEST_EQ (MANT_DIG)) \ + CHECK_SAME_NAN (TYPE, n456, s456); \ + if (CAN_TEST_EQ (MANT_DIG)) \ + CHECK_SAME_NAN (TYPE, nemp, semp); \ + if (CAN_TEST_EQ (MANT_DIG)) \ + CHECK_SAME_NAN (TYPE, n123x, sx); \ + CHECK_DIFF_NAN (TYPE, n123, n456); \ + CHECK_DIFF_NAN (TYPE, n123, nemp); \ + CHECK_DIFF_NAN (TYPE, n123, n123x); \ + CHECK_DIFF_NAN (TYPE, n456, nemp); \ + CHECK_DIFF_NAN (TYPE, n456, n123x); \ + } \ + while (0) + +static int +do_test (void) +{ + int result = 0; + RUN_TESTS (float, strtof, nanf, FLT_MANT_DIG); + RUN_TESTS (double, strtod, nan, DBL_MANT_DIG); +#ifndef NO_LONG_DOUBLE + RUN_TESTS (long double, strtold, nanl, LDBL_MANT_DIG); +#endif + return result; +} + +#define TEST_FUNCTION do_test () +#include "../test-skeleton.c" Index: git/stdlib/Versions =================================================================== --- git.orig/stdlib/Versions +++ git/stdlib/Versions @@ -118,5 +118,6 @@ libc { # Used from other libraries __libc_secure_getenv; __call_tls_dtors; + __strtof_nan; __strtod_nan; __strtold_nan; } } Index: git/math/Makefile =================================================================== --- git.orig/math/Makefile +++ git/math/Makefile @@ -92,7 +92,9 @@ tests = test-matherr test-fenv atest-exp test-misc test-fpucw test-fpucw-ieee tst-definitions test-tgmath \ test-tgmath-ret bug-nextafter bug-nexttoward bug-tgmath1 \ test-tgmath-int test-tgmath2 test-powl tst-CMPLX tst-CMPLX2 test-snan \ - test-fenv-tls test-fenv-preserve test-fenv-return $(tests-static) + test-fenv-tls test-fenv-preserve test-fenv-return \ + test-nan-overflow test-nan-payload \ + $(tests-static) tests-static = test-fpucw-static test-fpucw-ieee-static # We do the `long double' tests only if this data type is available and # distinct from `double'.