gnu: sharutils: Fix CVE-2018-1000097.

* gnu/packages/patches/sharutils-CVE-2018-1000097.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it.
* gnu/packages/compression.scm (sharutils)[source](patches): Use it.

gnu/local.mk

@@ -1093,6 +1093,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/sdl-libx11-1.6.patch			\
   %D%/packages/patches/seq24-rename-mutex.patch			\
   %D%/packages/patches/shadow-CVE-2018-7169.patch		\
+  %D%/packages/patches/sharutils-CVE-2018-1000097.patch		\
   %D%/packages/patches/shishi-fix-libgcrypt-detection.patch	\
   %D%/packages/patches/slim-session.patch			\
   %D%/packages/patches/slim-config.patch			\

gnu/packages/compression.scm

@@ -533,6 +533,7 @@ decompressors when faced with corrupted input.")
       (method url-fetch)
       (uri (string-append "mirror://gnu/sharutils/sharutils-"
                           version ".tar.xz"))
+      (patches (search-patches "sharutils-CVE-2018-1000097.patch"))
       (sha256
        (base32
         "16isapn8f39lnffc3dp4dan05b7x6mnc76v6q5nn8ysxvvvwy19b"))))

gnu/packages/patches/sharutils-CVE-2018-1000097.patch

@@ -0,0 +1,21 @@
+Fix CVE-2018-1000097:
+
+https://security-tracker.debian.org/tracker/CVE-2018-1000097
+https://nvd.nist.gov/vuln/detail/CVE-2018-1000097
+
+Patch taken from upstream bug report:
+https://lists.gnu.org/archive/html/bug-gnu-utils/2018-02/msg00005.html
+
+diff --git a/src/unshar.c b/src/unshar.c
+index 80bc3a9..0fc3773 100644
+--- a/src/unshar.c
++++ b/src/unshar.c
+@@ -240,7 +240,7 @@ find_archive (char const * name, FILE * file, off_t start)
+       off_t position = ftello (file);
+ 
+       /* Read next line, fail if no more and no previous process.  */
+-      if (!fgets (rw_buffer, BUFSIZ, file))
++      if (!fgets (rw_buffer, rw_base_size, file))
+ 	{
+ 	  if (!start)
+ 	    error (0, 0, _("Found no shell commands in %s"), name);