aarch64: Don't assert on long sysreg names

This patch fixes an assertion failure on long system register operands
in the AArch64 backend. See the new testcase for an input which
reproduces the issue.

gas/ChangeLog:

	* config/tc-aarch64.c (parse_sys_reg): Don't assert when parsing
	a long system register.
	(parse_sys_ins_reg): Likewise.
	(sysreg_hash_insert): New.
	(md_begin): Use sysreg_hash_insert() to ensure all system
	registers are no longer than the maximum length at startup.
	* testsuite/gas/aarch64/invalid-sysreg-assert.d: New test.
	* testsuite/gas/aarch64/invalid-sysreg-assert.l: Error output.
	* testsuite/gas/aarch64/invalid-sysreg-assert.s: Input.

include/ChangeLog:

	* opcode/aarch64.h (AARCH64_MAX_SYSREG_NAME_LEN): New.

5 files changed, 49 insertions, 13 deletions

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 03628a6..07def54 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,15 @@
+2020-08-10  Alex Coplan  <alex.coplan@arm.com>
+
+	* config/tc-aarch64.c (parse_sys_reg): Don't assert when parsing
+	a long system register.
+	(parse_sys_ins_reg): Likewise.
+	(sysreg_hash_insert): New.
+	(md_begin): Use sysreg_hash_insert() to ensure all system
+	registers are no longer than the maximum length at startup.
+	* testsuite/gas/aarch64/invalid-sysreg-assert.d: New test.
+	* testsuite/gas/aarch64/invalid-sysreg-assert.l: Error output.
+	* testsuite/gas/aarch64/invalid-sysreg-assert.s: Input.
+
 2020-08-10  Przemyslaw Wirkus  <przemyslaw.wirkus@arm.com>
 
 	* config/tc-aarch64.c (parse_sys_reg): Call to
diff --git a/gas/config/tc-aarch64.c b/gas/config/tc-aarch64.c
index a46a474..fdac91e 100644
--- a/gas/config/tc-aarch64.c
+++ b/gas/config/tc-aarch64.c
@@ -4100,17 +4100,21 @@ parse_sys_reg (char **str, struct hash_control *sys_regs,
 	       uint32_t* flags)
 {
   char *p, *q;
-  char buf[32];
+  char buf[AARCH64_MAX_SYSREG_NAME_LEN];
   const aarch64_sys_reg *o;
   int value;
 
   p = buf;
   for (q = *str; ISALNUM (*q) || *q == '_'; q++)
-    if (p < buf + 31)
+    if (p < buf + (sizeof (buf) - 1))
       *p++ = TOLOWER (*q);
   *p = '\0';
-  /* Assert that BUF be large enough.  */
-  gas_assert (p - buf == q - *str);
+
+  /* If the name is longer than AARCH64_MAX_SYSREG_NAME_LEN then it cannot be a
+     valid system register.  This is enforced by construction of the hash
+     table.  */
+  if (p - buf != q - *str)
+    return PARSE_FAIL;
 
   o = hash_find (sys_regs, buf);
   if (!o)
@@ -4161,15 +4165,21 @@ static const aarch64_sys_ins_reg *
 parse_sys_ins_reg (char **str, struct hash_control *sys_ins_regs)
 {
   char *p, *q;
-  char buf[32];
+  char buf[AARCH64_MAX_SYSREG_NAME_LEN];
   const aarch64_sys_ins_reg *o;
 
   p = buf;
   for (q = *str; ISALNUM (*q) || *q == '_'; q++)
-    if (p < buf + 31)
+    if (p < buf + (sizeof (buf) - 1))
       *p++ = TOLOWER (*q);
   *p = '\0';
 
+  /* If the name is longer than AARCH64_MAX_SYSREG_NAME_LEN then it cannot be a
+     valid system register.  This is enforced by construction of the hash
+     table.  */
+  if (p - buf != q - *str)
+    return NULL;
+
   o = hash_find (sys_ins_regs, buf);
   if (!o)
     return NULL;
@@ -8621,6 +8631,13 @@ checked_hash_insert (struct hash_control *table, const char *key, void *value)
 }
 
 static void
+sysreg_hash_insert (struct hash_control *table, const char *key, void *value)
+{
+  gas_assert (strlen (key) < AARCH64_MAX_SYSREG_NAME_LEN);
+  checked_hash_insert (table, key, value);
+}
+
+static void
 fill_instruction_hash_table (void)
 {
   aarch64_opcode *opcode = aarch64_opcode_table;
@@ -8694,36 +8711,36 @@ md_begin (void)
   fill_instruction_hash_table ();
 
   for (i = 0; aarch64_sys_regs[i].name != NULL; ++i)
-    checked_hash_insert (aarch64_sys_regs_hsh, aarch64_sys_regs[i].name,
+    sysreg_hash_insert (aarch64_sys_regs_hsh, aarch64_sys_regs[i].name,
 			 (void *) (aarch64_sys_regs + i));
 
   for (i = 0; aarch64_pstatefields[i].name != NULL; ++i)
-    checked_hash_insert (aarch64_pstatefield_hsh,
+    sysreg_hash_insert (aarch64_pstatefield_hsh,
 			 aarch64_pstatefields[i].name,
 			 (void *) (aarch64_pstatefields + i));
 
   for (i = 0; aarch64_sys_regs_ic[i].name != NULL; i++)
-    checked_hash_insert (aarch64_sys_regs_ic_hsh,
+    sysreg_hash_insert (aarch64_sys_regs_ic_hsh,
 			 aarch64_sys_regs_ic[i].name,
 			 (void *) (aarch64_sys_regs_ic + i));
 
   for (i = 0; aarch64_sys_regs_dc[i].name != NULL; i++)
-    checked_hash_insert (aarch64_sys_regs_dc_hsh,
+    sysreg_hash_insert (aarch64_sys_regs_dc_hsh,
 			 aarch64_sys_regs_dc[i].name,
 			 (void *) (aarch64_sys_regs_dc + i));
 
   for (i = 0; aarch64_sys_regs_at[i].name != NULL; i++)
-    checked_hash_insert (aarch64_sys_regs_at_hsh,
+    sysreg_hash_insert (aarch64_sys_regs_at_hsh,
 			 aarch64_sys_regs_at[i].name,
 			 (void *) (aarch64_sys_regs_at + i));
 
   for (i = 0; aarch64_sys_regs_tlbi[i].name != NULL; i++)
-    checked_hash_insert (aarch64_sys_regs_tlbi_hsh,
+    sysreg_hash_insert (aarch64_sys_regs_tlbi_hsh,
 			 aarch64_sys_regs_tlbi[i].name,
 			 (void *) (aarch64_sys_regs_tlbi + i));
 
   for (i = 0; aarch64_sys_regs_sr[i].name != NULL; i++)
-    checked_hash_insert (aarch64_sys_regs_sr_hsh,
+    sysreg_hash_insert (aarch64_sys_regs_sr_hsh,
 			 aarch64_sys_regs_sr[i].name,
 			 (void *) (aarch64_sys_regs_sr + i));
 
diff --git a/gas/testsuite/gas/aarch64/invalid-sysreg-assert.d b/gas/testsuite/gas/aarch64/invalid-sysreg-assert.d
new file mode 100644
index 0000000..a6279bb
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/invalid-sysreg-assert.d
@@ -0,0 +1,3 @@
+#name: don't assert on long system register
+#source: invalid-sysreg-assert.s
+#error_output: invalid-sysreg-assert.l
diff --git a/gas/testsuite/gas/aarch64/invalid-sysreg-assert.l b/gas/testsuite/gas/aarch64/invalid-sysreg-assert.l
new file mode 100644
index 0000000..b604910
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/invalid-sysreg-assert.l
@@ -0,0 +1,2 @@
+[^:]*: Assembler messages:
+.*: Error: unknown or missing system register name at operand 1 -- `msr 00000000000000000000000000000000'
diff --git a/gas/testsuite/gas/aarch64/invalid-sysreg-assert.s b/gas/testsuite/gas/aarch64/invalid-sysreg-assert.s
new file mode 100644
index 0000000..8b3706f
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/invalid-sysreg-assert.s
@@ -0,0 +1,2 @@
+// This input caused an assertion failure in parse_sys_reg.
+msr 00000000000000000000000000000000