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authorArmin Kuster <akuster@mvista.com>2021-01-14 11:51:17 -0800
committerSteve Sakoman <steve@sakoman.com>2021-01-19 04:22:10 -1000
commit3cabc58417cb5d69a018aec9c818fec63db18336 (patch)
tree74e05107f469b8fffe3c2bb0f4d0993b7d2b27be
parent16e30186afd13650407c67a2f6a598412f214bd1 (diff)
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glibc: Security fix for CVE-2020-29573
Source: glibc.org MR: 107580 Type: Security Fix Disposition: Backport from https://sourceware.org/git/?p=glibc.git;a=commit;h=681900d29683722b1cb0a8e565a0585846ec5a61 ChangeID: 7bc5edb2e1947ac0774a453000a1568bbe3bb7d2 Description: Fixedup to match 2.31 context. ldbl2mpn.c is in i386 for this version Signed-off-by: Armin Kuster <akuster@mvista.com> Signed-off-by: Steve Sakoman <steve@sakoman.com>
-rw-r--r--meta/recipes-core/glibc/glibc/CVE-2020-29573.patch128
-rw-r--r--meta/recipes-core/glibc/glibc_2.31.bb1
2 files changed, 129 insertions, 0 deletions
diff --git a/meta/recipes-core/glibc/glibc/CVE-2020-29573.patch b/meta/recipes-core/glibc/glibc/CVE-2020-29573.patch
new file mode 100644
index 0000000000..1e75f2d29d
--- /dev/null
+++ b/meta/recipes-core/glibc/glibc/CVE-2020-29573.patch
@@ -0,0 +1,128 @@
+From 681900d29683722b1cb0a8e565a0585846ec5a61 Mon Sep 17 00:00:00 2001
+From: Florian Weimer <fweimer@redhat.com>
+Date: Tue, 22 Sep 2020 19:07:48 +0200
+Subject: [PATCH] x86: Harden printf against non-normal long double values (bug
+ 26649)
+
+The behavior of isnan/__builtin_isnan on bit patterns that do not
+correspond to something that the CPU would produce from valid inputs
+is currently under-defined in the toolchain. (The GCC built-in and
+glibc disagree.)
+
+The isnan check in PRINTF_FP_FETCH in stdio-common/printf_fp.c
+assumes the GCC behavior that returns true for non-normal numbers
+which are not specified as NaN. (The glibc implementation returns
+false for such numbers.)
+
+At present, passing non-normal numbers to __mpn_extract_long_double
+causes this function to produce irregularly shaped multi-precision
+integers, triggering undefined behavior in __printf_fp_l.
+
+With GCC 10 and glibc 2.32, this behavior is not visible because
+__builtin_isnan is used, which avoids calling
+__mpn_extract_long_double in this case. This commit updates the
+implementation of __mpn_extract_long_double so that regularly shaped
+multi-precision integers are produced in this case, avoiding
+undefined behavior in __printf_fp_l.
+
+Upstream-Status: Backport [git://sourceware.org/git/glibc.git]
+CVE: CVE-2020-29573
+Signed-off-By: Armin Kuster <akuster@mvista.com>
+
+---
+ sysdeps/x86/Makefile | 4 ++
+ sysdeps/x86/ldbl2mpn.c | 8 ++++
+ sysdeps/x86/tst-ldbl-nonnormal-printf.c | 52 +++++++++++++++++++++++++
+ 3 files changed, 64 insertions(+)
+ create mode 100644 sysdeps/x86/tst-ldbl-nonnormal-printf.c
+
+Index: git/sysdeps/x86/Makefile
+===================================================================
+--- git.orig/sysdeps/x86/Makefile
++++ git/sysdeps/x86/Makefile
+@@ -9,6 +9,10 @@ tests += tst-get-cpu-features tst-get-cp
+ tests-static += tst-get-cpu-features-static
+ endif
+
++ifeq ($(subdir),math)
++tests += tst-ldbl-nonnormal-printf
++endif # $(subdir) == math
++
+ ifeq ($(subdir),setjmp)
+ gen-as-const-headers += jmp_buf-ssp.sym
+ sysdep_routines += __longjmp_cancel
+Index: git/sysdeps/x86/tst-ldbl-nonnormal-printf.c
+===================================================================
+--- /dev/null
++++ git/sysdeps/x86/tst-ldbl-nonnormal-printf.c
+@@ -0,0 +1,52 @@
++/* Test printf with x86-specific non-normal long double value.
++ Copyright (C) 2020 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 <support/check.h>
++
++/* Fill the stack with non-zero values. This makes a crash in
++ snprintf more likely. */
++static void __attribute__ ((noinline, noclone))
++fill_stack (void)
++{
++ char buffer[65536];
++ memset (buffer, 0xc0, sizeof (buffer));
++ asm ("" ::: "memory");
++}
++
++static int
++do_test (void)
++{
++ fill_stack ();
++
++ long double value;
++ memcpy (&value, "\x00\x04\x00\x00\x00\x00\x00\x00\x00\x04", 10);
++
++ char buf[30];
++ int ret = snprintf (buf, sizeof (buf), "%Lg", value);
++ TEST_COMPARE (ret, strlen (buf));
++ if (strcmp (buf, "nan") != 0)
++ /* If snprintf does not recognize the non-normal number as a NaN,
++ it has added the missing explicit MSB. */
++ TEST_COMPARE_STRING (buf, "3.02201e-4624");
++ return 0;
++}
++
++#include <support/test-driver.c>
+Index: git/sysdeps/i386/ldbl2mpn.c
+===================================================================
+--- git.orig/sysdeps/i386/ldbl2mpn.c
++++ git/sysdeps/i386/ldbl2mpn.c
+@@ -115,6 +115,12 @@ __mpn_extract_long_double (mp_ptr res_pt
+ && res_ptr[N - 1] == 0)
+ /* Pseudo zero. */
+ *expt = 0;
+-
++ else
++ /* The sign bit is explicit, but add it in case it is missing in
++ the input. Otherwise, callers will not be able to produce the
++ expected multi-precision integer layout by shifting the sign
++ bit into the MSB. */
++ res_ptr[N - 1] |= (mp_limb_t) 1 << (LDBL_MANT_DIG - 1
++ - ((N - 1) * BITS_PER_MP_LIMB));
+ return N;
+ }
diff --git a/meta/recipes-core/glibc/glibc_2.31.bb b/meta/recipes-core/glibc/glibc_2.31.bb
index 3a0d60abf8..067d4de64a 100644
--- a/meta/recipes-core/glibc/glibc_2.31.bb
+++ b/meta/recipes-core/glibc/glibc_2.31.bb
@@ -42,6 +42,7 @@ SRC_URI = "${GLIBC_GIT_URI};branch=${SRCBRANCH};name=glibc \
file://0028-inject-file-assembly-directives.patch \
file://0029-locale-prevent-maybe-uninitialized-errors-with-Os-BZ.patch \
file://CVE-2020-29562.patch \
+ file://CVE-2020-29573.patch \
"
S = "${WORKDIR}/git"
B = "${WORKDIR}/build-${TARGET_SYS}"