Avoid crashes due to invalid coding-system

* src/fileio.c (choose_write_coding_system)
(Finsert_file_contents): Check validity of coding-system-for-write
and coding-system-for-read bound by the caller.  (Bug#21602)

1 files changed, 8 insertions, 1 deletions

diff --git a/src/fileio.c b/src/fileio.c
index e4b255a53ac..65aaf572fd7 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -3470,7 +3470,10 @@ by calling `format-decode', which see.  */)
       mtime = time_error_value (save_errno);
       st.st_size = -1;
       if (!NILP (Vcoding_system_for_read))
-        Fset (Qbuffer_file_coding_system, Vcoding_system_for_read);
+        {
+          CHECK_CODING_SYSTEM (Vcoding_system_for_read);
+          Fset (Qbuffer_file_coding_system, Vcoding_system_for_read);
+        }
       goto notfound;
     }
 
@@ -4526,6 +4529,7 @@ choose_write_coding_system (Lisp_Object start, Lisp_Object end, Lisp_Object file
   else if (!NILP (Vcoding_system_for_write))
     {
       val = Vcoding_system_for_write;
+      CHECK_CODING_SYSTEM (val);
       if (coding_system_require_warning
           && !NILP (Ffboundp (Vselect_safe_coding_system_function)))
         /* Confirm that VAL can surely encode the current region.  */
@@ -4574,6 +4578,9 @@ choose_write_coding_system (Lisp_Object start, Lisp_Object end, Lisp_Object file
           using_default_coding = 1;
         }
 
+      if (!NILP (val))
+        CHECK_CODING_SYSTEM (val);
+
       if (! NILP (val) && ! force_raw_text)
         {
           Lisp_Object spec, attrs;