[PATCH][2.24] Drop GLIBC_TUNABLES in setxid processes

[Siddhesh Poyarekar]

Drop the GLIBC_TUNABLES environment variable from the environment of
setxid processes to avoid passing it on to non-setxid children.  This
prevents potentially insecure tunables in the GLIBC_TUNABLES envvar
from crossing over into a child that may use a libc that has tunables
support.

Tested on x86_64.  If this has an ack, I'll backport it to 2.23
and 2.22.  Distro maintainers please feel free to backport it further
down if needed.

Siddhesh

	* sysdeps/generic/unsecvars.h: Add GLIBC_TUNABLES.
---
 sysdeps/generic/unsecvars.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sysdeps/generic/unsecvars.h b/sysdeps/generic/unsecvars.h
index d5b8119..3e56538 100644
--- a/sysdeps/generic/unsecvars.h
+++ b/sysdeps/generic/unsecvars.h
@@ -4,6 +4,7 @@
 #define UNSECURE_ENVVARS \
   "GCONV_PATH\0"							      \
   "GETCONF_DIR\0"							      \
+  "GLIBC_TUNABLES\0"							      \
   "HOSTALIASES\0"							      \
   "LD_AUDIT\0"								      \
   "LD_DEBUG\0"								      \
-- 
2.7.4