http://sourceware.org/ml/gdb-patches/2012-09/msg00632.html
Subject: [PATCH 2/4] Add a check to ensure that a type may fit into host memory


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Hi,

This is part two of the bitpos expansion patch.  This implements checks
in some places in the code to ensure that a type size in ULONGEST is
small enough to fit into host memory.  Tested for regressions on x86_64
Fedora 16.

Regards,
Siddhesh

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gdb/ChangeLog

	* alpha-tdep.c (alpha_push_dummy_call) Check for underflow in
	SP.
	* cp-valprint (cp_print_value): Ensure BASECLASS fits into
	size_t.
	* dwarf2loc.c (read_pieced_value): Ensure that THIS_SIZE fits
	into size_t.
	(write_pieced_value): Likewise.
	* findcmd.c (parse_find_args): Ensure PATTERN_BUF_SIZE fits into
	size_t.
	* p-valprint (pascal_object_print_value): Ensure BASECLASS fits
	into size_t.
	* utils.c (ulongest_fits_host_or_error): New function to find if
	a ULONGEST number fits into size_t.
	* utils.h: Declare ulongest_fits_host_or_error.
	* valops.c (search_struct_method): Ensure BASECLASS fits into
	size_t.
	* value.c (allocate_value_lazy): Ensure TYPE fits into size_t.
	(allocate_value_contents): Likewise.
	(set_value_enclosing_type): Ensure NEW_ENCL_TYPE fits into
	size_t.
	* vax-tdep.c (vax_return_value): Ensure that TYPE fits into
	size_t.

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Index: gdb-8.0/gdb/alpha-tdep.c
===================================================================
--- gdb-8.0.orig/gdb/alpha-tdep.c	2017-08-19 20:07:45.469330496 +0200
+++ gdb-8.0/gdb/alpha-tdep.c	2017-08-19 20:07:50.670379152 +0200
@@ -414,6 +414,13 @@
     accumulate_size = 0;
   else
     accumulate_size -= sizeof(arg_reg_buffer);
+
+  /* Check for underflow.  */
+  if (sp - accumulate_size > sp)
+    error (_("Insufficient memory in GDB host for arguments, "
+	     "need %s bytes, but less than %s bytes available."),
+	   plongest (accumulate_size), plongest (CORE_ADDR_MAX - sp));
+
   sp -= accumulate_size;
 
   /* Keep sp aligned to a multiple of 16 as the ABI requires.  */
Index: gdb-8.0/gdb/cp-valprint.c
===================================================================
--- gdb-8.0.orig/gdb/cp-valprint.c	2017-08-19 20:07:45.470330505 +0200
+++ gdb-8.0/gdb/cp-valprint.c	2017-08-19 20:07:50.670379152 +0200
@@ -537,6 +537,8 @@
 		  gdb_byte *buf;
 		  struct cleanup *back_to;
 
+		  ulongest_fits_host_or_error (TYPE_LENGTH (baseclass));
+
 		  buf = (gdb_byte *) xmalloc (TYPE_LENGTH (baseclass));
 		  back_to = make_cleanup (xfree, buf);
 
Index: gdb-8.0/gdb/findcmd.c
===================================================================
--- gdb-8.0.orig/gdb/findcmd.c	2017-08-19 20:07:45.472330524 +0200
+++ gdb-8.0/gdb/findcmd.c	2017-08-19 20:07:50.672379171 +0200
@@ -186,6 +186,7 @@
 	  size_t current_offset = pattern_buf_end - pattern_buf;
 
 	  pattern_buf_size = pattern_buf_size_need * 2;
+	  ulongest_fits_host_or_error (pattern_buf_size);
 	  pattern_buf = (gdb_byte *) xrealloc (pattern_buf, pattern_buf_size);
 	  pattern_buf_end = pattern_buf + current_offset;
 	}
Index: gdb-8.0/gdb/p-valprint.c
===================================================================
--- gdb-8.0.orig/gdb/p-valprint.c	2017-08-19 20:07:45.472330524 +0200
+++ gdb-8.0/gdb/p-valprint.c	2017-08-19 20:07:50.673379180 +0200
@@ -772,6 +772,7 @@
 	      gdb_byte *buf;
 	      struct cleanup *back_to;
 
+	      ulongest_fits_host_or_error (TYPE_LENGTH (baseclass));
 	      buf = (gdb_byte *) xmalloc (TYPE_LENGTH (baseclass));
 	      back_to = make_cleanup (xfree, buf);
 
Index: gdb-8.0/gdb/utils.c
===================================================================
--- gdb-8.0.orig/gdb/utils.c	2017-08-19 20:07:45.473330533 +0200
+++ gdb-8.0/gdb/utils.c	2017-08-19 20:07:50.673379180 +0200
@@ -2776,6 +2776,18 @@
   return addr;
 }
 
+/* Ensure that the input NUM is not larger than the maximum capacity of the
+   host system.  We choose SIZE_MAX / 8 as a conservative estimate of the size
+   of a resource that a system may allocate.  */
+void
+ulongest_fits_host_or_error (ULONGEST num)
+{
+  if (num > SIZE_MAX / 8)
+    error (_("Insufficient memory in host GDB for object of size %s bytes, "
+	     "maximum allowed %s bytes."), pulongest (num),
+	   pulongest (SIZE_MAX / 8));
+}
+
 char *
 gdb_realpath (const char *filename)
 {
Index: gdb-8.0/gdb/valops.c
===================================================================
--- gdb-8.0.orig/gdb/valops.c	2017-08-19 20:07:45.474330542 +0200
+++ gdb-8.0/gdb/valops.c	2017-08-19 20:07:50.674379190 +0200
@@ -2100,6 +2100,7 @@
 	      struct cleanup *back_to;
 	      CORE_ADDR address;
 
+	      ulongest_fits_host_or_error (TYPE_LENGTH (baseclass));
 	      tmp = (gdb_byte *) xmalloc (TYPE_LENGTH (baseclass));
 	      back_to = make_cleanup (xfree, tmp);
 	      address = value_address (*arg1p);
Index: gdb-8.0/gdb/value.c
===================================================================
--- gdb-8.0.orig/gdb/value.c	2017-08-19 20:07:45.476330561 +0200
+++ gdb-8.0/gdb/value.c	2017-08-19 20:07:50.675379199 +0200
@@ -936,6 +936,7 @@
      description correctly.  */
   check_typedef (type);
 
+  ulongest_fits_host_or_error (TYPE_LENGTH (type));
   val = XCNEW (struct value);
   val->contents = NULL;
   val->next = all_values;
@@ -1033,6 +1034,8 @@
 static void
 allocate_value_contents (struct value *val)
 {
+  ulongest_fits_host_or_error (TYPE_LENGTH (val->enclosing_type));
+
   if (!val->contents)
     {
       check_type_length_before_alloc (val->enclosing_type);
@@ -3093,6 +3096,7 @@
   if (TYPE_LENGTH (new_encl_type) > TYPE_LENGTH (value_enclosing_type (val)))
     {
       check_type_length_before_alloc (new_encl_type);
+      ulongest_fits_host_or_error (TYPE_LENGTH (new_encl_type));
       val->contents
 	= (gdb_byte *) xrealloc (val->contents, TYPE_LENGTH (new_encl_type));
     }
Index: gdb-8.0/gdb/vax-tdep.c
===================================================================
--- gdb-8.0.orig/gdb/vax-tdep.c	2017-08-19 20:07:45.476330561 +0200
+++ gdb-8.0/gdb/vax-tdep.c	2017-08-19 20:07:50.675379199 +0200
@@ -219,6 +219,7 @@
 	  ULONGEST addr;
 
 	  regcache_raw_read_unsigned (regcache, VAX_R0_REGNUM, &addr);
+	  ulongest_fits_host_or_error (TYPE_LENGTH (type));
 	  read_memory (addr, readbuf, len);
 	}
 
Index: gdb-8.0/gdb/defs.h
===================================================================
--- gdb-8.0.orig/gdb/defs.h	2017-08-19 20:07:45.476330561 +0200
+++ gdb-8.0/gdb/defs.h	2017-08-19 20:07:50.676379208 +0200
@@ -750,4 +750,6 @@
 
 #include "utils.h"
 
+extern void ulongest_fits_host_or_error (ULONGEST num);
+
 #endif /* #ifndef DEFS_H */