From: Andreas Arnez <arnez@linux.vnet.ibm.com>
Date: Fri, 12 Dec 2014 13:14:20 +0000 (+0100)
Subject: gdbserver: Prevent stale/random values in register cache
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=098dbe61246fd65ea5e3825d77afb31d52c43153;p=binutils-gdb.git

gdbserver: Prevent stale/random values in register cache

When fetch_inferior_registers does not update all registers, this
patch assures that no stale register values remain in the register
cache.  On Linux platforms using the regsets interface, when one of
the ptrace calls used for fetching the register values returns an
error, this patch also avoids copying the random data returned from
ptrace into the register cache.  All unfetched registers are marked
"unavailable" instead.

gdb/gdbserver/ChangeLog:

	* linux-low.c (regsets_fetch_inferior_registers): Do not invoke
	the regset's store function when ptrace returned an error.
	* regcache.c (get_thread_regcache): Invalidate register cache
	before fetching inferior's registers.
---

diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 7471dae583d..54caa55ef12 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,10 @@
+2014-12-12  Andreas Arnez  <arnez@linux.vnet.ibm.com>
+
+	* linux-low.c (regsets_fetch_inferior_registers): Do not invoke
+	the regset's store function when ptrace returned an error.
+	* regcache.c (get_thread_regcache): Invalidate register cache
+	before fetching inferior's registers.
+
 2014-12-12  Andreas Arnez  <arnez@linux.vnet.ibm.com>
 
 	* linux-low.c (regsets_fetch_inferior_registers): Rephrase
diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
index 164b0f66240..c1b53ff42d1 100644
--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -4255,8 +4255,6 @@ regsets_fetch_inferior_registers (struct regsets_info *regsets_info,
 	      /* If we get EIO on a regset, do not try it again for
 		 this process mode.  */
 	      disable_regset (regsets_info, regset);
-	      free (buf);
-	      continue;
 	    }
 	  else
 	    {
@@ -4266,9 +4264,12 @@ regsets_fetch_inferior_registers (struct regsets_info *regsets_info,
 	      perror (s);
 	    }
 	}
-      else if (regset->type == GENERAL_REGS)
-	saw_general_regs = 1;
-      regset->store_function (regcache, buf);
+      else
+	{
+	  if (regset->type == GENERAL_REGS)
+	    saw_general_regs = 1;
+	  regset->store_function (regcache, buf);
+	}
       free (buf);
     }
   if (saw_general_regs)
diff --git a/gdb/gdbserver/regcache.c b/gdb/gdbserver/regcache.c
index 718ae8c3c9b..8c874f0c2a4 100644
--- a/gdb/gdbserver/regcache.c
+++ b/gdb/gdbserver/regcache.c
@@ -52,6 +52,9 @@ get_thread_regcache (struct thread_info *thread, int fetch)
       struct thread_info *saved_thread = current_thread;
 
       current_thread = thread;
+      /* Invalidate all registers, to prevent stale left-overs.  */
+      memset (regcache->register_status, REG_UNAVAILABLE,
+	      regcache->tdesc->num_registers);
       fetch_inferior_registers (regcache, -1);
       current_thread = saved_thread;
       regcache->registers_valid = 1;