gnu: zstd: Downgrade to 1.4.4 and make security graft saner.

* gnu/packages/patches/zstd-CVE-2021-24031_CVE-2021-24032.patch: New patch.
* gnu/local.mk (dist_patch_DATA): Register it.
* gnu/packages/compression.scm (zstd-1.4.9): Remove.
(zstd/fixed): New variable. Apply patch.
(zstd)[replacement]: Graft with zstd/fixed.

gnu/local.mk

@@ -1824,6 +1824,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/yggdrasil-extra-config.patch	\
   %D%/packages/patches/ytnef-CVE-2021-3403.patch	\
   %D%/packages/patches/ytnef-CVE-2021-3404.patch	\
+  %D%/packages/patches/zstd-CVE-2021-24031_CVE-2021-24032.patch	\
   %D%/packages/patches/zziplib-CVE-2018-16548.patch
 
 MISC_DISTRO_FILES =				\

gnu/packages/compression.scm

@@ -1409,7 +1409,7 @@ or junctions, and always follows hard links.")
                            "v" version "/zstd-" version ".tar.gz"))
        (sha256
         (base32 "05ckxap00qvc0j51d3ci38150cxsw82w7s9zgd5fgzspnzmp1vsr"))))
-    (replacement zstd-1.4.9)
+    (replacement zstd/fixed)
     (build-system gnu-build-system)
     (outputs '("out"                    ;1.2MiB executables and documentation
                "lib"                    ;1.2MiB shared library and headers
@@ -1469,21 +1469,16 @@ speed.")
                    license:public-domain ; zlibWrapper/examples/fitblk*
                    license:zlib))))      ; zlibWrapper/{gz*.c,gzguts.h}
 
-(define-public zstd-1.4.9
+(define zstd/fixed
   (package
     (inherit zstd)
-    (name "zstd")
-    (version "1.4.9")
     (source
      (origin
-       (method url-fetch)
+       (inherit (package-source zstd))
-       (uri (string-append "https://github.com/facebook/zstd/releases/download/"
+       (patches
-                           "v" version "/zstd-" version ".tar.gz"))
+        (search-patches
-       (sha256
+         ;; From Ubuntu focal-security
-        (base32 "14yj7309gsvg39rki4xqnd6w5idmqi0655v1fc0mk1m2kvhp9b19"))))
+         "zstd-CVE-2021-24031_CVE-2021-24032.patch"))))))
-    (arguments
-     (substitute-keyword-arguments (package-arguments zstd)
-       ((#:tests? _ #t) #f)))))
 
 (define-public pzstd
   (package/inherit zstd

gnu/packages/patches/zstd-CVE-2021-24031_CVE-2021-24032.patch

@@ -0,0 +1,68 @@
+Description: fix race condition allowing attackers to access destination file
+ This commit addresses https://github.com/facebook/zstd/issues/2491.
+ .
+ Note that a downside of this solution is that it is global: `umask()` affects
+ all file creation calls in the process. I believe this is safe since
+ `fileio.c` functions should only ever be used in the zstd binary, and these
+ are (almost) the only files ever created by zstd, and AIUI they're only
+ created in a single thread. So we can get away with messing with global state.
+ .
+ Note that this doesn't change the permissions of files created by `dibio.c`.
+ I'm not sure what those should be...
+Author: W. Felix Handte <w@felixhandte.com>
+Origin: upstream
+Bug: https://github.com/facebook/zstd/issues/2491
+Bug-Debian: https://github.com/facebook/zstd/issues/2491
+Applied-Upstream: commit:a774c5797399040af62db21d8a9b9769e005430e
+Reviewed-by: Étienne Mollier <etienne.mollier@mailoo.org>
+Last-Update: 2021-03-03
+---
+This patch header follows DEP-3: http://dep.debian.net/deps/dep3/
+--- a/programs/fileio.c
++++ b/programs/fileio.c
+@@ -606,11 +606,11 @@ FIO_openDstFile(FIO_prefs_t* const prefs
+             FIO_remove(dstFileName);
+     }   }
+ 
+-    {   FILE* const f = fopen( dstFileName, "wb" );
++    {   const int old_umask = UTIL_umask(0177); /* u-x,go-rwx */
++        FILE* const f = fopen( dstFileName, "wb" );
++        UTIL_umask(old_umask);
+         if (f == NULL) {
+             DISPLAYLEVEL(1, "zstd: %s: %s\n", dstFileName, strerror(errno));
+-        } else if(srcFileName != NULL && strcmp (srcFileName, stdinmark)) {
+-            chmod(dstFileName, 00600);
+         }
+         return f;
+     }
+--- a/programs/util.c
++++ b/programs/util.c
+@@ -54,6 +54,15 @@ int UTIL_getFileStat(const char* infilen
+     return 1;
+ }
+ 
++int UTIL_umask(int mode) {
++#if PLATFORM_POSIX_VERSION > 0
++    return umask(mode);
++#else
++    /* do nothing, fake return value */
++    return mode;
++#endif
++}
++
+ int UTIL_setFileStat(const char *filename, stat_t *statbuf)
+ {
+     int res = 0;
+--- a/programs/util.h
++++ b/programs/util.h
+@@ -136,6 +136,10 @@ int UTIL_isSameFile(const char* file1, c
+ int UTIL_compareStr(const void *p1, const void *p2);
+ int UTIL_isCompressedFile(const char* infilename, const char *extensionList[]);
+ const char* UTIL_getFileExtension(const char* infilename);
++/**
++ * Wraps umask(). Does nothing when the platform doesn't have that concept.
++ */
++int UTIL_umask(int mode);
+ 
+ #ifndef _MSC_VER
+ U32 UTIL_isFIFO(const char* infilename);