diff --git a/libgcc/ChangeLog b/libgcc/ChangeLog
index 3f23e724b97c..778848ba5bc0 100644
--- a/libgcc/ChangeLog
+++ b/libgcc/ChangeLog
@@ -1,3 +1,9 @@
+2012-01-09  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* config/sparc/sol2-unwind.h (sparc64_is_sighandler): Check that the
+	purported sigacthandler address isn't null before dereferencing it.
+	(sparc_is_sighandler): Likewise.
+
 2012-01-09  Eric Botcazou  <ebotcazou@adacore.com>
 
 	PR ada/41929
diff --git a/libgcc/config/sparc/sol2-unwind.h b/libgcc/config/sparc/sol2-unwind.h
index ea4c541b8159..7d6bd221dd51 100644
--- a/libgcc/config/sparc/sol2-unwind.h
+++ b/libgcc/config/sparc/sol2-unwind.h
@@ -124,10 +124,9 @@ sparc64_is_sighandler (unsigned int *pc, void *cfa, int *nframes)
 	  /* This matches the call_user_handler pattern for Solaris 10.
 	     There are 2 cases so we look for the return address of the
 	     caller's caller frame in order to do more pattern matching.  */
-	  unsigned int sah_pattern
-	    = *(unsigned int *)(*(unsigned long *)(cfa + 176 + 15*8) - 4);
+	  unsigned long sah_address = *(unsigned long *)(cfa + 176 + 15*8);
 
-          if (sah_pattern == 0x92100019)
+          if (sah_address && *(unsigned int *)(sah_address - 4) == 0x92100019)
 	    /* This is the same setup as for Solaris 9, see below.  */
 	    *nframes = 3;
 	  else
@@ -302,10 +301,9 @@ sparc_is_sighandler (unsigned int *pc, void *cfa, int *nframes)
 	  /* This matches the call_user_handler pattern for Solaris 10.
 	     There are 2 cases so we look for the return address of the
 	     caller's caller frame in order to do more pattern matching.  */
-	  unsigned int sah_pattern
-	    = *(unsigned int *)(*(unsigned int *)(cfa + 96 + 15*4) - 4);
+	  unsigned int sah_address = *(unsigned int *)(cfa + 96 + 15*4);
 
-          if (sah_pattern == 0x92100019)
+          if (sah_address && *(unsigned int *)(sah_address - 4) == 0x92100019)
 	    /* This is the same setup as for Solaris 9, see below.  */
 	    *nframes = 3;
 	  else