[OE-core][dunfell 03/18] busybox: Fix for CVE-2021-42374

Steve Sakoman
2021-12-03T18:21:32Z

From: Pavel Zhukov <pavel.zhukov@huawei.com>

An out-of-bounds heap read in unlzma leads to information leak and
denial of service when crafted LZMA-compressed input is decompressed.
This can be triggered by any applet/format that internally supports
LZMA compression.

Reference: https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-42374

Signed-off-by: Pavel Zhukov <pavel.zhukov@huawei.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>
---
.../busybox/busybox/CVE-2021-42374.patch | 53 +++++++++++++++++++
meta/recipes-core/busybox/busybox_1.31.1.bb | 1 +
2 files changed, 54 insertions(+)
create mode 100644 meta/recipes-core/busybox/busybox/CVE-2021-42374.patch

diff --git a/meta/recipes-core/busybox/busybox/CVE-2021-42374.patch b/meta/recipes-core/busybox/busybox/CVE-2021-42374.patch
new file mode 100644
index 0000000000..aef8a3db85
--- /dev/null
+++ b/meta/recipes-core/busybox/busybox/CVE-2021-42374.patch
@@ -0,0 +1,53 @@
+From 04f052c56ded5ab6a904e3a264a73dc0412b2e78 Mon Sep 17 00:00:00 2001
+From: Denys Vlasenko <vda.linux@googlemail.com>
+Date: Tue, 15 Jun 2021 15:07:57 +0200
+Subject: [PATCH] unlzma: fix a case where we could read before beginning of
+ buffer
+Cc: pavel@zhukoff.net
+
+Testcase:
+
+ 21 01 01 00 00 00 00 00 e7 01 01 01 ef 00 df b6
+ 00 17 02 10 11 0f ff 00 16 00 00
+
+Unfortunately, the bug is not reliably causing a segfault,
+the behavior depends on what's in memory before the buffer.
+
+function old new delta
+unpack_lzma_stream 2762 2768 +6
+
+Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
+
+Signed-off-by: Pavel Zhukov <pavel.zhukov@huawei.com>
+
+CVE: CVE-2021-42374
+Upstream-Status: Backport [https://git.busybox.net/busybox/commit/?h=1_33_stable&id=d326be2850ea2bd78fe2c22d6c45c3b861d82937]
+Comment: testdata dropped because of binary format
+
+---
+ archival/libarchive/decompress_unlzma.c | 5 ++++-
+ testsuite/unlzma.tests | 17 +++++++++++++----
+ testsuite/unlzma_issue_3.lzma | Bin 0 -> 27 bytes
+ 3 files changed, 17 insertions(+), 5 deletions(-)
+ create mode 100644 testsuite/unlzma_issue_3.lzma
+
+diff --git a/archival/libarchive/decompress_unlzma.c b/archival/libarchive/decompress_unlzma.c
+index 0744f231a1d64d92676b0cada2342f88f3b39b31..fb5aac8fe9ea0c53e0c2d7a7cbd05a753e39bc9d 100644
+--- a/archival/libarchive/decompress_unlzma.c
++++ b/archival/libarchive/decompress_unlzma.c
+@@ -290,8 +290,11 @@ unpack_lzma_stream(transformer_state_t *xstate)
+ uint32_t pos;
+
+ pos = buffer_pos - rep0;
+- if ((int32_t)pos < 0)
++ if ((int32_t)pos < 0) {
+ pos += header.dict_size;
++ if ((int32_t)pos < 0)
++ goto bad;
++ }
+ match_byte = buffer[pos];
+ do {
+ int bit;
+--
+2.34.0
+
diff --git a/meta/recipes-core/busybox/busybox_1.31.1.bb b/meta/recipes-core/busybox/busybox_1.31.1.bb
index d9d5f4f96b..55c00eb483 100644
--- a/meta/recipes-core/busybox/busybox_1.31.1.bb
+++ b/meta/recipes-core/busybox/busybox_1.31.1.bb
@@ -52,6 +52,7 @@ SRC_URI = "https://busybox.net/downloads/busybox-${PV}.tar.bz2;name=tarball \
file://0001-hwclock-make-glibc-2.31-compatible.patch \
file://0001-decompress_gunzip-Fix-DoS-if-gzip-is-corrupt.patch \
file://0001-mktemp-add-tmpdir-option.patch \
+ file://CVE-2021-42374.patch \
"
SRC_URI_append_libc-musl = " file://musl.cfg "

--
2.25.1