gnu: busybox: Fix CVE-2021-28831.

* gnu/packages/patches/busybox-CVE-2021-28831.patch: New patch.
* gnu/local.mk (dist_patch_DATA): Register it.
* gnu/packages/busybox.scm (busybox): Apply it.

gnu/local.mk

@@ -872,6 +872,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/blender-2.79-python-3.7-fix.patch	\
   %D%/packages/patches/blender-2.79-python-3.8-fix.patch	\
   %D%/packages/patches/bpftrace-disable-bfd-disasm.patch	\
+  %D%/packages/patches/busybox-CVE-2021-28831.patch		\
   %D%/packages/patches/byobu-writable-status.patch		\
   %D%/packages/patches/cairo-CVE-2018-19876.patch		\
   %D%/packages/patches/cairo-CVE-2020-35492.patch		\

gnu/packages/busybox.scm

@@ -41,7 +41,8 @@
                     version ".tar.bz2"))
               (sha256
                (base32
-                "1vhd59qmrdyrr1q7rvxmyl96z192mxl089hi87yl0hcp6fyw8mwx"))))
+                "1vhd59qmrdyrr1q7rvxmyl96z192mxl089hi87yl0hcp6fyw8mwx"))
+              (patches (search-patches "busybox-CVE-2021-28831.patch"))))
     (build-system gnu-build-system)
     (arguments
      '(#:phases

gnu/packages/patches/busybox-CVE-2021-28831.patch

@@ -0,0 +1,57 @@
+From f25d254dfd4243698c31a4f3153d4ac72aa9e9bd Mon Sep 17 00:00:00 2001
+From: Samuel Sapalski <samuel.sapalski@nokia.com>
+Date: Wed, 3 Mar 2021 16:31:22 +0100
+Subject: 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 <samuel.sapalski@nokia.com>
+Signed-off-by: Peter Kaestle <peter.kaestle@nokia.com>
+Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
+---
+ 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)
+-- 
+cgit v1.2.1
+