Allow larger regblock sizes when saving tracefiles

The tracefile.c:trace_save function assumes trace_regblock_size won't
be larger than the MAX_TRACE_UPLOAD constant, used to size the buffer
which holds trace data.  This can cause buffer overruns when this is
not the case.  This patch changes this function so that the larger
size is used to size the buffer.

gdb/ChangeLog:
2018-08-06  Pedro Franco de Carvalho  <pedromfc@linux.ibm.com>

	* tracefile.c: Include common/byte-vector.h.
	(trace_save): Change type of buf to gdb::byte_vector.  Initialize
	with trace_regblock_size if needed.  Update uses of buf.

1 files changed, 23 insertions, 19 deletions

diff --git a/gdb/tracefile.c b/gdb/tracefile.c
index ecd2f5c..b367f6e 100644
--- a/gdb/tracefile.c
+++ b/gdb/tracefile.c
@@ -22,6 +22,7 @@
 #include "ctf.h"
 #include "exec.h"
 #include "regcache.h"
+#include "common/byte-vector.h"
 
 /* Helper macros.  */
 
@@ -67,7 +68,7 @@ trace_save (const char *filename, struct trace_file_writer *writer,
 
   ULONGEST offset = 0;
 #define MAX_TRACE_UPLOAD 2000
-  gdb_byte buf[MAX_TRACE_UPLOAD];
+  gdb::byte_vector buf (std::max (MAX_TRACE_UPLOAD, trace_regblock_size));
   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 
   /* If the target is to save the data to a file on its own, then just
@@ -144,7 +145,7 @@ trace_save (const char *filename, struct trace_file_writer *writer,
 	  /* We ask for big blocks, in the hopes of efficiency, but
 	     will take less if the target has packet size limitations
 	     or some such.  */
-	  gotten = target_get_raw_trace_data (buf, offset,
+	  gotten = target_get_raw_trace_data (buf.data (), offset,
 					      MAX_TRACE_UPLOAD);
 	  if (gotten < 0)
 	    error (_("Failure to get requested trace buffer data"));
@@ -152,7 +153,7 @@ trace_save (const char *filename, struct trace_file_writer *writer,
 	  if (gotten == 0)
 	    break;
 
-	  writer->ops->write_trace_buffer (writer, buf, gotten);
+	  writer->ops->write_trace_buffer (writer, buf.data (), gotten);
 
 	  offset += gotten;
 	}
@@ -163,7 +164,7 @@ trace_save (const char *filename, struct trace_file_writer *writer,
 	  /* Parse the trace buffers according to how data are stored
 	     in trace buffer in GDBserver.  */
 
-	  gotten = target_get_raw_trace_data (buf, offset, 6);
+	  gotten = target_get_raw_trace_data (buf.data (), offset, 6);
 
 	  if (gotten == 0)
 	    break;
@@ -171,10 +172,10 @@ trace_save (const char *filename, struct trace_file_writer *writer,
 	  /* Read the first six bytes in, which is the tracepoint
 	     number and trace frame size.  */
 	  tp_num = (uint16_t)
-	    extract_unsigned_integer (&buf[0], 2, byte_order);
+	    extract_unsigned_integer (&((buf.data ())[0]), 2, byte_order);
 
 	  tf_size = (uint32_t)
-	    extract_unsigned_integer (&buf[2], 4, byte_order);
+	    extract_unsigned_integer (&((buf.data ())[2]), 4, byte_order);
 
 	  writer->ops->frame_ops->start (writer, tp_num);
 	  gotten = 6;
@@ -192,7 +193,8 @@ trace_save (const char *filename, struct trace_file_writer *writer,
 		  /* We'll fetch one block each time, in order to
 		     handle the extremely large 'M' block.  We first
 		     fetch one byte to get the type of the block.  */
-		  gotten = target_get_raw_trace_data (buf, offset, 1);
+		  gotten = target_get_raw_trace_data (buf.data (),
+						      offset, 1);
 		  if (gotten < 1)
 		    error (_("Failure to get requested trace buffer data"));
 
@@ -205,13 +207,13 @@ trace_save (const char *filename, struct trace_file_writer *writer,
 		    {
 		    case 'R':
 		      gotten
-			= target_get_raw_trace_data (buf, offset,
+			= target_get_raw_trace_data (buf.data (), offset,
 						     trace_regblock_size);
 		      if (gotten < trace_regblock_size)
 			error (_("Failure to get requested trace"
 				 " buffer data"));
 
-		      TRACE_WRITE_R_BLOCK (writer, buf,
+		      TRACE_WRITE_R_BLOCK (writer, buf.data (),
 					   trace_regblock_size);
 		      break;
 		    case 'M':
@@ -221,7 +223,8 @@ trace_save (const char *filename, struct trace_file_writer *writer,
 			LONGEST t;
 			int j;
 
-			t = target_get_raw_trace_data (buf,offset, 10);
+			t = target_get_raw_trace_data (buf.data (),
+						       offset, 10);
 			if (t < 10)
 			  error (_("Failure to get requested trace"
 				   " buffer data"));
@@ -231,10 +234,10 @@ trace_save (const char *filename, struct trace_file_writer *writer,
 
 			gotten = 0;
 			addr = (ULONGEST)
-			  extract_unsigned_integer (buf, 8,
+			  extract_unsigned_integer (buf.data (), 8,
 						    byte_order);
 			mlen = (unsigned short)
-			  extract_unsigned_integer (&buf[8], 2,
+			  extract_unsigned_integer (&((buf.data ())[8]), 2,
 						    byte_order);
 
 			TRACE_WRITE_M_BLOCK_HEADER (writer, addr,
@@ -252,14 +255,15 @@ trace_save (const char *filename, struct trace_file_writer *writer,
 			    else
 			      read_length = mlen - j;
 
-			    t = target_get_raw_trace_data (buf,
+			    t = target_get_raw_trace_data (buf.data (),
 							   offset + j,
 							   read_length);
 			    if (t < read_length)
 			      error (_("Failure to get requested"
 				       " trace buffer data"));
 
-			    TRACE_WRITE_M_BLOCK_MEMORY (writer, buf,
+			    TRACE_WRITE_M_BLOCK_MEMORY (writer,
+							buf.data (),
 							read_length);
 
 			    j += read_length;
@@ -274,18 +278,18 @@ trace_save (const char *filename, struct trace_file_writer *writer,
 			LONGEST val;
 
 			gotten
-			  = target_get_raw_trace_data (buf, offset,
-						       12);
+			  = target_get_raw_trace_data (buf.data (),
+						       offset, 12);
 			if (gotten < 12)
 			  error (_("Failure to get requested"
 				   " trace buffer data"));
 
-			vnum  = (int) extract_signed_integer (buf,
+			vnum  = (int) extract_signed_integer (buf.data (),
 							      4,
 							      byte_order);
 			val
-			  = extract_signed_integer (&buf[4], 8,
-						    byte_order);
+			  = extract_signed_integer (&((buf.data ())[4]),
+						    8, byte_order);
 
 			TRACE_WRITE_V_BLOCK (writer, vnum, val);
 		      }