Re: [PATCH] hppa: Avoid manipulating function pointers from a traced process.

[Dmitry V. Levin]

On Wed, Sep 09, 2009 at 02:13:19PM -0400, Carlos O'Donell wrote:
 Architectures using function pointers, like hppa, may need to
 manipulate the function pointer to compute the result of a comparison.
 However, the SA_HANDLER function pointer exists only in the address
 space of the traced process, and can't be manipulated by strace. In
 order to prevent the compiler from generating code to manipulate
 SA_HANDLER we cast the function pointers to long.
 
 Please apply.

The change looks harmless for other architectures, so OK for me.


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[PATCH] hppa: Avoid manipulating function pointers from a traced process.

[Carlos O'Donell]

Architectures using function pointers, like hppa, may need to
manipulate the function pointer to compute the result of a comparison.
However, the SA_HANDLER function pointer exists only in the address
space of the traced process, and can't be manipulated by strace. In
order to prevent the compiler from generating code to manipulate
SA_HANDLER we cast the function pointers to long.

Please apply.

Cheers,
Carlos.
~~~
Fix function pointer comparison for hppa.

* signal.c (sys_sigaction): Cast function pointers to long.
(sys_rt_sigaction): Cast function pointers to long.
diff --git a/signal.c b/signal.c
index 76504f6..7ce4809 100644
--- a/signal.c
+++ b/signal.c
@@ -1121,11 +1121,19 @@ struct tcb *tcp;
 	else if (umove(tcp, addr, sa)  0)
 		tprintf({...});
 	else {
-		if (sa.SA_HANDLER == SIG_ERR)
+		/* Architectures using function pointers, like
+		 * hppa, may need to manipulate the function pointer
+		 * to compute the result of a comparison. However,
+		 * the SA_HANDLER function pointer exists only in 
+		 * the address space of the traced process, and can't
+		 * be manipulated by strace. In order to prevent the 
+		 * compiler from generating code to manipulate 
+		 * SA_HANDLER we cast the function pointers to long. */
+		if ((long)sa.SA_HANDLER == (long)SIG_ERR)
 			tprintf({SIG_ERR, );
-		else if (sa.SA_HANDLER == SIG_DFL)
+		else if ((long)sa.SA_HANDLER == (long)SIG_DFL)
 			tprintf({SIG_DFL, );
-		else if (sa.SA_HANDLER == SIG_IGN) {
+		else if ((long)sa.SA_HANDLER == (long)SIG_IGN) {
 #ifndef USE_PROCFS
 			if (tcp-u_arg[0] == SIGTRAP) {
 tcp-flags |= TCB_SIGTRAPPED;
@@ -1931,12 +1939,19 @@ sys_rt_sigaction(struct tcb *tcp)
 		tprintf({...});
 		goto after_sa;
 	}
-
-	if (sa.__sa_handler == SIG_ERR)
+	/* Architectures using function pointers, like
+	 * hppa, may need to manipulate the function pointer
+	 * to compute the result of a comparison. However,
+	 * the SA_HANDLER function pointer exists only in 
+	 * the address space of the traced process, and can't
+	 * be manipulated by strace. In order to prevent the 
+	 * compiler from generating code to manipulate 
+	 * SA_HANDLER we cast the function pointers to long. */
+	if ((long)sa.__sa_handler == (long)SIG_ERR)
 		tprintf({SIG_ERR, );
-	else if (sa.__sa_handler == SIG_DFL)
+	else if ((long)sa.__sa_handler == (long)SIG_DFL)
 		tprintf({SIG_DFL, );
-	else if (sa.__sa_handler == SIG_IGN)
+	else if ((long)sa.__sa_handler == (long)SIG_IGN)
 		tprintf({SIG_IGN, );
 	else
 		tprintf({%#lx, , (long) sa.__sa_handler);
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