gnu: musl: Fix CVE-2016-8859.

* gnu/packages/patches/musl-CVE-2016-8859.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/musl.scm (musl)[source]: Use it.

gnu/local.mk

@@ -712,6 +712,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/mupdf-CVE-2016-6265.patch		\
   %D%/packages/patches/mupdf-CVE-2016-6525.patch		\
   %D%/packages/patches/mupen64plus-ui-console-notice.patch	\
+  %D%/packages/patches/musl-CVE-2016-8859.patch			\
   %D%/packages/patches/mutt-store-references.patch		\
   %D%/packages/patches/nasm-no-ps-pdf.patch			\
   %D%/packages/patches/net-tools-bitrot.patch			\

gnu/packages/musl.scm

@@ -32,6 +32,7 @@
               (method url-fetch)
               (uri (string-append "http://www.musl-libc.org/releases/"
                                   name "-" version ".tar.gz"))
+              (patches (search-patches "musl-CVE-2016-8859.patch"))
               (sha256
                (base32
                 "1ymhxkskivzph0q34zadwfglc5gyahqajm7chqqn2zraxv3lgr4p"))))

gnu/packages/patches/musl-CVE-2016-8859.patch

@@ -0,0 +1,81 @@
+Fix CVE-2016-8859:
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-8859
+
+Patch copied from upstream source repository:
+
+http://git.musl-libc.org/cgit/musl/commit/?id=c3edc06d1e1360f3570db9155d6b318ae0d0f0f7
+
+From c3edc06d1e1360f3570db9155d6b318ae0d0f0f7 Mon Sep 17 00:00:00 2001
+From: Rich Felker <dalias@aerifal.cx>
+Date: Thu, 6 Oct 2016 18:34:58 -0400
+Subject: [PATCH] fix missing integer overflow checks in regexec buffer size
+ computations
+
+most of the possible overflows were already ruled out in practice by
+regcomp having already succeeded performing larger allocations.
+however at least the num_states*num_tags multiplication can clearly
+overflow in practice. for safety, check them all, and use the proper
+type, size_t, rather than int.
+
+also improve comments, use calloc in place of malloc+memset, and
+remove bogus casts.
+---
+ src/regex/regexec.c | 23 ++++++++++++++++++-----
+ 1 file changed, 18 insertions(+), 5 deletions(-)
+
+diff --git a/src/regex/regexec.c b/src/regex/regexec.c
+index 16c5d0a..dd52319 100644
+--- a/src/regex/regexec.c
++++ b/src/regex/regexec.c
+@@ -34,6 +34,7 @@
+ #include <wchar.h>
+ #include <wctype.h>
+ #include <limits.h>
++#include <stdint.h>
+ 
+ #include <regex.h>
+ 
+@@ -206,11 +207,24 @@ tre_tnfa_run_parallel(const tre_tnfa_t *tnfa, const void *string,
+ 
+   /* Allocate memory for temporary data required for matching.	This needs to
+      be done for every matching operation to be thread safe.  This allocates
+-     everything in a single large block from the stack frame using alloca()
+-     or with malloc() if alloca is unavailable. */
++     everything in a single large block with calloc(). */
+   {
+-    int tbytes, rbytes, pbytes, xbytes, total_bytes;
++    size_t tbytes, rbytes, pbytes, xbytes, total_bytes;
+     char *tmp_buf;
++
++    /* Ensure that tbytes and xbytes*num_states cannot overflow, and that
++     * they don't contribute more than 1/8 of SIZE_MAX to total_bytes. */
++    if (num_tags > SIZE_MAX/(8 * sizeof(int) * tnfa->num_states))
++      goto error_exit;
++
++    /* Likewise check rbytes. */
++    if (tnfa->num_states+1 > SIZE_MAX/(8 * sizeof(*reach_next)))
++      goto error_exit;
++
++    /* Likewise check pbytes. */
++    if (tnfa->num_states > SIZE_MAX/(8 * sizeof(*reach_pos)))
++      goto error_exit;
++
+     /* Compute the length of the block we need. */
+     tbytes = sizeof(*tmp_tags) * num_tags;
+     rbytes = sizeof(*reach_next) * (tnfa->num_states + 1);
+@@ -221,10 +235,9 @@ tre_tnfa_run_parallel(const tre_tnfa_t *tnfa, const void *string,
+       + (rbytes + xbytes * tnfa->num_states) * 2 + tbytes + pbytes;
+ 
+     /* Allocate the memory. */
+-    buf = xmalloc((unsigned)total_bytes);
++    buf = calloc(total_bytes, 1);
+     if (buf == NULL)
+       return REG_ESPACE;
+-    memset(buf, 0, (size_t)total_bytes);
+ 
+     /* Get the various pointers within tmp_buf (properly aligned). */
+     tmp_tags = (void *)buf;
+-- 
+2.10.1
+