From 0f4ec05ed07865c86a261e453e78a508afca8ce4 Mon Sep 17 00:00:00 2001 From: Peter Korsgaard Date: Tue, 6 Apr 2021 15:11:59 +0200 Subject: [PATCH] package/busybox: add upstream gunzip security fix Fixes the following security issue: - CVE-2021-28831: decompress_gunzip.c in BusyBox through 1.32.1 mishandles the error bit on the huft_build result pointer, with a resultant invalid free or segmentation fault, via malformed gzip data. Signed-off-by: Peter Korsgaard --- ...ss_gunzip-Fix-DoS-if-gzip-is-corrupt.patch | 58 +++++++++++++++++++ package/busybox/busybox.mk | 3 + 2 files changed, 61 insertions(+) create mode 100644 package/busybox/0004-decompress_gunzip-Fix-DoS-if-gzip-is-corrupt.patch diff --git a/package/busybox/0004-decompress_gunzip-Fix-DoS-if-gzip-is-corrupt.patch b/package/busybox/0004-decompress_gunzip-Fix-DoS-if-gzip-is-corrupt.patch new file mode 100644 index 0000000000..d40cb4d6cd --- /dev/null +++ b/package/busybox/0004-decompress_gunzip-Fix-DoS-if-gzip-is-corrupt.patch @@ -0,0 +1,58 @@ +From f25d254dfd4243698c31a4f3153d4ac72aa9e9bd Mon Sep 17 00:00:00 2001 +From: Samuel Sapalski +Date: Wed, 3 Mar 2021 16:31:22 +0100 +Subject: [PATCH] decompress_gunzip: Fix DoS if gzip is corrupt + +On certain corrupt gzip files, huft_build will set the error bit on +the result pointer. If afterwards abort_unzip is called huft_free +might run into a segmentation fault or an invalid pointer to +free(p). + +In order to mitigate this, we check in huft_free if the error bit +is set and clear it before the linked list is freed. + +Signed-off-by: Samuel Sapalski +Signed-off-by: Peter Kaestle +Signed-off-by: Denys Vlasenko +Signed-off-by: Peter Korsgaard +--- + archival/libarchive/decompress_gunzip.c | 12 ++++++++++-- + 1 file changed, 10 insertions(+), 2 deletions(-) + +diff --git a/archival/libarchive/decompress_gunzip.c b/archival/libarchive/decompress_gunzip.c +index eb3b64930..e93cd5005 100644 +--- a/archival/libarchive/decompress_gunzip.c ++++ b/archival/libarchive/decompress_gunzip.c +@@ -220,10 +220,20 @@ static const uint8_t border[] ALIGN1 = { + * each table. + * t: table to free + */ ++#define BAD_HUFT(p) ((uintptr_t)(p) & 1) ++#define ERR_RET ((huft_t*)(uintptr_t)1) + static void huft_free(huft_t *p) + { + huft_t *q; + ++ /* ++ * If 'p' has the error bit set we have to clear it, otherwise we might run ++ * into a segmentation fault or an invalid pointer to free(p) ++ */ ++ if (BAD_HUFT(p)) { ++ p = (huft_t*)((uintptr_t)(p) ^ (uintptr_t)(ERR_RET)); ++ } ++ + /* Go through linked list, freeing from the malloced (t[-1]) address. */ + while (p) { + q = (--p)->v.t; +@@ -289,8 +299,6 @@ static unsigned fill_bitbuffer(STATE_PARAM unsigned bitbuffer, unsigned *current + * or a valid pointer to a Huffman table, ORed with 0x1 if incompete table + * is given: "fixed inflate" decoder feeds us such data. + */ +-#define BAD_HUFT(p) ((uintptr_t)(p) & 1) +-#define ERR_RET ((huft_t*)(uintptr_t)1) + static huft_t* huft_build(const unsigned *b, const unsigned n, + const unsigned s, const struct cp_ext *cp_ext, + unsigned *m) +-- +2.20.1 + diff --git a/package/busybox/busybox.mk b/package/busybox/busybox.mk index 032e487267..e979ac4f4b 100644 --- a/package/busybox/busybox.mk +++ b/package/busybox/busybox.mk @@ -11,6 +11,9 @@ BUSYBOX_LICENSE = GPL-2.0, bzip2-1.0.4 BUSYBOX_LICENSE_FILES = LICENSE archival/libarchive/bz/LICENSE BUSYBOX_CPE_ID_VENDOR = busybox +# 0004-decompress_gunzip-Fix-DoS-if-gzip-is-corrupt.patch +BUSYBOX_IGNORE_CVES += CVE-2021-28831 + define BUSYBOX_HELP_CMDS @echo ' busybox-menuconfig - Run BusyBox menuconfig' endef -- 2.30.2