klibc: patch CVE-2021-31870

Details: https://nvd.nist.gov/vuln/detail/CVE-2021-31870

Pick patch mentioned in the nvd report.

Signed-off-by: Gyorgy Sarvari <skandigraun@gmail.com>

meta-initramfs/recipes-devtools/klibc/files/CVE-2021-31870.patch

@@ -0,0 +1,45 @@
+From 15c0e066ac8a75bdb3189dd5d77dc0f3539afefd Mon Sep 17 00:00:00 2001
+From: Ben Hutchings <ben@decadent.org.uk>
+Date: Wed, 28 Apr 2021 04:29:50 +0200
+Subject: [PATCH] calloc: Fail if multiplication overflows
+
+calloc() multiplies its 2 arguments together and passes the result to
+malloc().  Since the factors and product both have type size_t, this
+can result in an integer overflow and subsequent buffer overflow.
+Check for this and fail if it happens.
+
+CVE-2021-31870
+
+CVE: CVE-2021-31870
+Upstream-Status: Backport [https://git.kernel.org/pub/scm/libs/klibc/klibc.git/commit/?id=292650f04c2b5348b4efbad61fb014ed09b4f3f2]
+
+Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
+---
+ usr/klibc/calloc.c | 11 ++++++++---
+ 1 file changed, 8 insertions(+), 3 deletions(-)
+
+diff --git a/usr/klibc/calloc.c b/usr/klibc/calloc.c
+index 53dcc6b..4a81cda 100644
+--- a/usr/klibc/calloc.c
++++ b/usr/klibc/calloc.c
+@@ -2,12 +2,17 @@
+  * calloc.c
+  */
+ 
++#include <errno.h>
+ #include <stdlib.h>
+ #include <string.h>
+ 
+-/* FIXME: This should look for multiplication overflow */
+-
+ void *calloc(size_t nmemb, size_t size)
+ {
+-	return zalloc(nmemb * size);
++	unsigned long prod;
++
++	if (__builtin_umull_overflow(nmemb, size, &prod)) {
++		errno = ENOMEM;
++		return NULL;
++	}
++	return zalloc(prod);
+ }

meta-initramfs/recipes-devtools/klibc/klibc.inc

@@ -21,6 +21,7 @@ SRC_URI = "${KERNELORG_MIRROR}/linux/libs/klibc/2.0/klibc-${PV}.tar.xz \
            file://0001-klibc-Kbuild-Accept-EXTRA_KLIBCAFLAGS.patch \
            file://cross-clang.patch \
            file://0001-workaround-for-overlapping-sections-in-binary.patch \
+           file://CVE-2021-31870.patch \
            "
 
 ARMPATCHES ?= ""