Re: [PATCH] libkmod: Avoid calling syscall() with -1

[Jan Luebbe <jlu@pengutronix.de>]

On Thu, May 02, 2013 at 01:21:08PM -0300, Lucas De Marchi wrote:
> Indeed. But I had already a patch for that, just waiting the bug
> reporter to test it:
> 
> http://bugs.funtoo.org/browse/FL-534
> 
> And the patch:
> http://bugs.funtoo.org/secure/attachment/11098/dont-call-libc.diff

In that patch, the new #ifndef is never used, as __NR_finit_module is
defined a few lines up.

This one looks better, but failes to compile:
http://bugs.funtoo.org/secure/attachment/11099/0001-missing-Don-t-call-syscall-with-syscallno-1.patch
libkmod/missing.h:27:17: error: '__NR_finit_module' undeclared (first use in this function)

I've changed your patch a little (put the real call into the #else branch).
With this version, I don't see the problem any more.

----

From: Lucas De Marchi <lucas.de.marchi@gmail.com>
Date: Thu, 2 May 2013 13:22:57 -0300
Subject: [PATCH] missing: Don't call syscall() with syscallno == -1

Reported-by: Jean-Francis Roy <jeanfrancis@funtoo.org>
Reported-by: Jan Luebbe <jlu@pengutronix.de>
---
 libkmod/missing.h |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/libkmod/missing.h b/libkmod/missing.h
index edb88b9..b31af84 100644
--- a/libkmod/missing.h
+++ b/libkmod/missing.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <errno.h>
 #include <unistd.h>
 #include <sys/syscall.h>
 
@@ -15,13 +16,14 @@
 # define MODULE_INIT_IGNORE_VERMAGIC 2
 #endif
 
-#ifndef __NR_finit_module
-# define __NR_finit_module -1
-#endif
-
 #ifndef HAVE_FINIT_MODULE
 static inline int finit_module(int fd, const char *uargs, int flags)
 {
+#ifndef __NR_finit_module
+	errno = ENOSYS;
+	return -1;
+#else
 	return syscall(__NR_finit_module, fd, uargs, flags);
+#endif
 }
 #endif

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