[PATH] nios2: Fix parsing of pseudo-instructions

[Henry Wong <henry at stuffedcow dot net>]

The Nios II assembler handles pseudo-instructions by "suitable fiddling
with the operands". When a malformed pseudo-instruction is used (too few
operands), nios2_modify_arg/nios2_negate_arg blindly modifies operands
that may not exist, causing a segfault. This patch checks that a
pseudo-instruction has enough operands before trying to modify them, for
cases where it matters.


Changes:

* config/tc-nios2.c (nios2_modify_arg, nios2_negate_arg): Fix segfault
when parsing Nios II pseudo-instructions that have missing arguments
* testsuite/gas/nios2/illegal_pseudoinst.s: New test for illegal Nios II
pseudo-instructions
* testsuite/gas/nios2/illegal_pseudoinst.l: stderr output
* testsuite/gas/nios2/nios2.exp: Changed so the above new test is run.


>From 29f77a83fe34aba7736afa28420ef61191ac9b1b Mon Sep 17 00:00:00 2001
From: Henry Wong <henry@stuffedcow.net>
Date: Wed, 27 Sep 2017 17:55:50 -0400
Subject: [PATCH] nios2: Fix parsing of pseudo-instructions with missing
 arguments

---
 gas/config/tc-nios2.c                        | 18 +++++++++++
 gas/testsuite/gas/nios2/illegal_pseudoinst.l | 35 ++++++++++++++++++++++
 gas/testsuite/gas/nios2/illegal_pseudoinst.s | 45 ++++++++++++++++++++++++++++
 gas/testsuite/gas/nios2/nios2.exp            |  1 +
 4 files changed, 99 insertions(+)
 create mode 100644 gas/testsuite/gas/nios2/illegal_pseudoinst.l
 create mode 100644 gas/testsuite/gas/nios2/illegal_pseudoinst.s

diff --git a/gas/config/tc-nios2.c b/gas/config/tc-nios2.c
index 4ac3eaaf..d7a4f934 100644
--- a/gas/config/tc-nios2.c
+++ b/gas/config/tc-nios2.c
@@ -3157,6 +3157,15 @@ nios2_modify_arg (char **parsed_args, const char *modifier,
 		  int unused ATTRIBUTE_UNUSED, int ndx)
 {
   char *tmp = parsed_args[ndx];
+  int i;
+
+  /* Don't modify past end of argument list */
+  for (i=0;i<=ndx;i++) {
+    if (parsed_args[i] == NULL) {
+      parsed_args[ndx] = NULL;    /* Don't free */
+      return;
+    }
+  }
 
   parsed_args[ndx] = concat (tmp, modifier, (char *) NULL);
 }
@@ -3167,6 +3176,15 @@ nios2_negate_arg (char **parsed_args, const char *modifier ATTRIBUTE_UNUSED,
 		  int unused ATTRIBUTE_UNUSED, int ndx)
 {
   char *tmp = parsed_args[ndx];
+  int i;
+
+  /* Don't modify past end of argument list */
+  for (i=0;i<=ndx;i++) {
+    if (parsed_args[i] == NULL) {
+      parsed_args[ndx] = NULL;    /* Don't free */
+      return;
+    }
+  }
 
   parsed_args[ndx] = concat ("~(", tmp, ")+1", (char *) NULL);
 }
diff --git a/gas/testsuite/gas/nios2/illegal_pseudoinst.l b/gas/testsuite/gas/nios2/illegal_pseudoinst.l
new file mode 100644
index 00000000..7d4ffdff
--- /dev/null
+++ b/gas/testsuite/gas/nios2/illegal_pseudoinst.l
@@ -0,0 +1,35 @@
+.*illegal_pseudoinst.s: Assembler messages:
+.*illegal_pseudoinst.s:5: Error: missing argument
+.*illegal_pseudoinst.s:6: Error: expecting , near r2
+.*illegal_pseudoinst.s:6: Error: missing argument
+.*illegal_pseudoinst.s:7: Error: missing argument
+.*illegal_pseudoinst.s:8: Error: expecting , near r2
+.*illegal_pseudoinst.s:8: Error: missing argument
+.*illegal_pseudoinst.s:9: Error: missing argument
+.*illegal_pseudoinst.s:10: Error: missing argument
+.*illegal_pseudoinst.s:11: Error: missing argument
+.*illegal_pseudoinst.s:14: Error: missing argument
+.*illegal_pseudoinst.s:15: Error: missing argument
+.*illegal_pseudoinst.s:16: Error: expecting , near r2
+.*illegal_pseudoinst.s:16: Error: missing argument
+.*illegal_pseudoinst.s:17: Error: missing argument
+.*illegal_pseudoinst.s:18: Error: missing argument
+.*illegal_pseudoinst.s:19: Error: missing argument
+.*illegal_pseudoinst.s:22: Error: missing argument
+.*illegal_pseudoinst.s:23: Error: missing argument
+.*illegal_pseudoinst.s:24: Error: missing argument
+.*illegal_pseudoinst.s:25: Error: missing argument
+.*illegal_pseudoinst.s:26: Error: missing argument
+.*illegal_pseudoinst.s:27: Error: missing argument
+.*illegal_pseudoinst.s:28: Error: missing argument
+.*illegal_pseudoinst.s:29: Error: missing argument
+.*illegal_pseudoinst.s:30: Error: missing argument
+.*illegal_pseudoinst.s:31: Error: missing argument
+.*illegal_pseudoinst.s:34: Error: missing argument
+.*illegal_pseudoinst.s:35: Error: missing argument
+.*illegal_pseudoinst.s:36: Error: unknown register 
+.*illegal_pseudoinst.s:37: Error: missing argument
+.*illegal_pseudoinst.s:38: Error: missing argument
+.*illegal_pseudoinst.s:41: Error: missing argument
+.*illegal_pseudoinst.s:42: Error: missing argument
+.*illegal_pseudoinst.s:43: Error: missing argument
diff --git a/gas/testsuite/gas/nios2/illegal_pseudoinst.s b/gas/testsuite/gas/nios2/illegal_pseudoinst.s
new file mode 100644
index 00000000..94b48cbe
--- /dev/null
+++ b/gas/testsuite/gas/nios2/illegal_pseudoinst.s
@@ -0,0 +1,45 @@
+# Source file used to test missing (and illegal) operands for pseudo-instructions.
+
+foo:
+# nios2_modify_arg
+	cmpgti r2, r3,
+	cmpgtui r2, r2
+	cmplei r2, r3,
+	cmpleui r2, r2
+	cmpgti ,,
+	cmplei ,
+	cmpleui
+
+# nios2_negate_arg
+	subi Lorem ipsum dolor sit amet, consectetur adipiscing elit,
+	subi r2, r2,
+	subi r2, r2
+	subi ,,
+	subi ,
+	subi
+
+# nios2_swap_args
+	bgt r0, r2,
+	bgtu ,,
+	ble , r0,
+	bleu foo,,
+	cmpgt r2, r3,
+	cmpgtu r2,,
+	cmple , r3,
+	cmpleu ,,
+	bgtu ,
+	ble
+
+# nios2_insert_arg
+	movi  ,
+	movhi r0,
+	movui ,r2
+	movia ,
+	movi
+
+# nios2_append_arg
+	mov r0,
+	mov ,
+	mov
+
+
diff --git a/gas/testsuite/gas/nios2/nios2.exp b/gas/testsuite/gas/nios2/nios2.exp
index 061d610c..e2cd332a 100644
--- a/gas/testsuite/gas/nios2/nios2.exp
+++ b/gas/testsuite/gas/nios2/nios2.exp
@@ -22,6 +22,7 @@ if { [istarget nios2-*-*] } {
     run_dump_tests [lsort [glob -nocomplain $srcdir/$subdir/*.d]]
     
     run_list_test "illegal" ""
+    run_list_test "illegal_pseudoinst" ""
     run_list_test "warn_nobreak" ""
     run_list_test "warn_noat" ""
     run_list_test "movi" ""
-- 
2.13.5