printenv: ignore bogus variable names

Exposed by env a=b=c printenv a=b.

* src/printenv.c (main): Silently reject = in names.
* tests/misc/printenv: Test for it.
* NEWS: Document this.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/printenv.c b/src/printenv.c
index b0f0154b2..acf09bdc7 100644
--- a/src/printenv.c
+++ b/src/printenv.c
@@ -125,6 +125,10 @@ main (int argc, char **argv)
         {
           bool matched = false;
 
+          /* 'printenv a=b' is silent, even if 'a=b=c' is in environ.  */
+          if (strchr (argv[i], '='))
+            continue;
+
           for (env = environ; *env; ++env)
             {
               ep = *env;