[PATCH] Remove more instances of unsafe alloca

[PATCH] Remove more instances of unsafe alloca

[Siddhesh Poyarekar]

[-- Attachment #1: Type: text/plain, Size: 593 bytes --]

Hi,

I found another couple of instances of unsafe alloca usage in gdb, both
to do with trying to allocate memory on stack for a baseclass type. The
fix is on the lines of what was done in the following changeset:

http://sourceware.org/ml/gdb-cvs/2012-07/msg00044.html

I have verified that the fix does not cause any regressions on x86_64.
OK to commit?

Regards,
Siddhesh

gdb/ChangeLog:

2012-07-23  Siddhesh Poyarekar  <siddhesh@redhat.com>

	* p-valprint.c (pascal_object_print_value): Replace potentially
	unsafe alloca with xmalloc/xfree.
	* valops.c (search_struct_method): Likewise.

[-- Attachment #2: alloca-cleanup.patch --]
[-- Type: text/x-patch, Size: 1929 bytes --]

? alloca-cleanup.patch
Index: gdb/p-valprint.c
===================================================================
RCS file: /cvs/src/src/gdb/p-valprint.c,v
retrieving revision 1.100
diff -u -r1.100 p-valprint.c
--- gdb/p-valprint.c	18 May 2012 21:02:49 -0000	1.100
+++ gdb/p-valprint.c	23 Jul 2012 12:34:37 -0000
@@ -797,8 +797,11 @@
 
 	  if (boffset < 0 || boffset >= TYPE_LENGTH (type))
 	    {
-	      /* FIXME (alloc): not safe is baseclass is really really big. */
-	      gdb_byte *buf = alloca (TYPE_LENGTH (baseclass));
+	      gdb_byte *buf;
+	      struct cleanup *back_to;
+
+	      buf = xmalloc (TYPE_LENGTH (baseclass));
+	      back_to = make_cleanup (xfree, buf);
 
 	      base_valaddr = buf;
 	      if (target_read_memory (address + boffset, buf,
@@ -807,6 +810,7 @@
 	      address = address + boffset;
 	      thisoffset = 0;
 	      boffset = 0;
+	      do_cleanups (back_to);
 	    }
 	  else
 	    base_valaddr = valaddr;
Index: gdb/valops.c
===================================================================
RCS file: /cvs/src/src/gdb/valops.c,v
retrieving revision 1.297
diff -u -r1.297 valops.c
--- gdb/valops.c	24 Jun 2012 07:28:10 -0000	1.297
+++ gdb/valops.c	23 Jul 2012 12:34:40 -0000
@@ -2281,8 +2281,13 @@
 
 	  if (offset < 0 || offset >= TYPE_LENGTH (type))
 	    {
-	      gdb_byte *tmp = alloca (TYPE_LENGTH (baseclass));
-	      CORE_ADDR address = value_address (*arg1p);
+	      gdb_byte *tmp;
+	      struct cleanup *back_to;
+	      CORE_ADDR address;
+
+	      tmp = xmalloc (TYPE_LENGTH (baseclass));
+	      back_to = make_cleanup (xfree, tmp);
+	      address = value_address (*arg1p);
 
 	      if (target_read_memory (address + offset,
 				      tmp, TYPE_LENGTH (baseclass)) != 0)
@@ -2293,6 +2298,7 @@
 							  address + offset);
 	      base_valaddr = value_contents_for_printing (base_val);
 	      this_offset = 0;
+	      do_cleanups (back_to);
 	    }
 	  else
 	    {

Re: [PATCH] Remove more instances of unsafe alloca

[Tom Tromey]

>>>>> "Siddhesh" == Siddhesh Poyarekar <siddhesh@redhat.com> writes:

Siddhesh> 2012-07-23  Siddhesh Poyarekar  <siddhesh@redhat.com>
Siddhesh> 	* p-valprint.c (pascal_object_print_value): Replace potentially
Siddhesh> 	unsafe alloca with xmalloc/xfree.
Siddhesh> 	* valops.c (search_struct_method): Likewise.

Ok.  Thanks.

Tom

Re: [PATCH] Remove more instances of unsafe alloca

[Siddhesh Poyarekar]

On Mon, 23 Jul 2012 08:07:22 -0600, Tom wrote:
> >>>>> "Siddhesh" == Siddhesh Poyarekar <siddhesh@redhat.com> writes:
> 
> Siddhesh> 2012-07-23  Siddhesh Poyarekar  <siddhesh@redhat.com>
> Siddhesh> 	* p-valprint.c (pascal_object_print_value): Replace
> Siddhesh> potentially unsafe alloca with xmalloc/xfree.
> Siddhesh> 	* valops.c (search_struct_method): Likewise.
> 
> Ok.  Thanks.
> 

Committed:

http://sourceware.org/ml/gdb-cvs/2012-07/msg00182.html

Regards,
Siddhesh