bug#27101: [PATCH] gnu: rxvt-unicode: Disable an unwanted code execution vector.

[Leo Famulari]

* gnu/packages/patches/rxvt-unicode-escape-sequences.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/xdisorg.scm (rxvt-unicode)[source]: Use it.
---
 gnu/local.mk                                       |  1 +
 .../patches/rxvt-unicode-escape-sequences.patch    | 35 ++++++++++++++++++++++
 gnu/packages/xdisorg.scm                           |  1 +
 3 files changed, 37 insertions(+)
 create mode 100644 gnu/packages/patches/rxvt-unicode-escape-sequences.patch

diff --git a/gnu/local.mk b/gnu/local.mk
index 0ef6e2af9..ee043d0c6 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -966,6 +966,7 @@ dist_patch_DATA =                                           
\
   %D%/packages/patches/ruby-puma-ignore-broken-test.patch       \
   %D%/packages/patches/ruby-rack-ignore-failing-test.patch      \
   %D%/packages/patches/ruby-tzinfo-data-ignore-broken-test.patch\
+  %D%/packages/patches/rxvt-unicode-escape-sequences.patch     \
   %D%/packages/patches/scheme48-tests.patch                    \
   %D%/packages/patches/scotch-test-threading.patch             \
   %D%/packages/patches/screen-fix-info-syntax-error.patch      \
diff --git a/gnu/packages/patches/rxvt-unicode-escape-sequences.patch 
b/gnu/packages/patches/rxvt-unicode-escape-sequences.patch
new file mode 100644
index 000000000..064dd51e2
--- /dev/null
+++ b/gnu/packages/patches/rxvt-unicode-escape-sequences.patch
@@ -0,0 +1,35 @@
+This patch prevents a code execution vector involving terminal escape
+sequences when rxvt-unicode is in "secure mode".
+
+This change was spurred by the following conversation on the
+oss-security mailing list:
+
+Problem description and proof of concept:
+http://seclists.org/oss-sec/2017/q2/190
+
+Upstream response:
+http://seclists.org/oss-sec/2017/q2/291
+
+Patch copied from upstream source repository:
+http://cvs.schmorp.de/rxvt-unicode/src/command.C?r1=1.582&r2=1.583
+
+--- rxvt-unicode/src/command.C 2016/07/14 05:33:26     1.582
++++ rxvt-unicode/src/command.C 2017/05/18 02:43:18     1.583
+@@ -2695,7 +2695,7 @@
+         /* kidnapped escape sequence: Should be 8.3.48 */
+       case C1_ESA:            /* ESC G */
+         // used by original rxvt for rob nations own graphics mode
+-        if (cmd_getc () == 'Q')
++        if (cmd_getc () == 'Q' && option (Opt_insecure))
+           tt_printf ("\033G0\012");   /* query graphics - no graphics */
+         break;
+ 
+@@ -2914,7 +2914,7 @@
+         break;
+ 
+       case CSI_CUB:           /* 8.3.18: (1) CURSOR LEFT */
+-      case CSI_HPB:           /* 8.3.59: (1) CHARACTER POSITION BACKWARD */
++      case CSI_HPB:           /* 8.3.59: (1) CHARACTER POSITION BACKWARD */
+ #ifdef ISO6429
+         arg[0] = -arg[0];
+ #else                         /* emulate common DEC VTs */
diff --git a/gnu/packages/xdisorg.scm b/gnu/packages/xdisorg.scm
index ad919a6b2..a2230c4e9 100644
--- a/gnu/packages/xdisorg.scm
+++ b/gnu/packages/xdisorg.scm
@@ -682,6 +682,7 @@ compact configuration syntax.")
               (method url-fetch)
               (uri (string-append "http://dist.schmorp.de/rxvt-unicode/Attic/";
                                   name "-" version ".tar.bz2"))
+              (patches (search-patches "rxvt-unicode-escape-sequences.patch"))
               (sha256
                (base32
                 "1pddjn5ynblwfrdmskylrsxb9vfnk3w4jdnq2l8xn2pspkljhip9"))))
-- 
2.13.0