linux-kernel - Re: [PATCH]: Cleanup: Remove gcc format string warnings when compiling with -Wformat-security

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Message-ID: <adak584jzw3.fsf@cisco.com>
Date:	Thu, 05 Feb 2009 14:13:32 -0800
From:	Roland Dreier <rdreier@...co.com>
To:	Floris Kraak <randakar@...il.com>
Cc:	Robert Hancock <hancockrwd@...il.com>,
	Sam Ravnborg <sam@...nborg.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Trivial Patch Monkey <trivial@...nel.org>,
	Andreas Schwab <schwab@...e.de>
Subject: Re: [PATCH]: Cleanup: Remove gcc format string warnings when compiling  with -Wformat-security

 > Here's the patch that I get when I blindly patch every single location
 > that emits this warning.

I would strongly prefer to do this with a little more care.  For example
the b43/main.c change:

 > --- a/drivers/net/wireless/b43/main.c
 > +++ b/drivers/net/wireless/b43/main.c
 > @@ -2005,9 +2005,9 @@ static void b43_print_fw_helptext(struct b43_wl
 > *wl, bool error)
 >  	       "http://linuxwireless.org/en/users/Drivers/b43#devicefirmware "
 >  	       "and download the latest firmware (version 4).\n";
 >  	if (error)
 > -		b43err(wl, text);
 > +		b43err(wl, "%s", text);
 >  	else
 > -		b43warn(wl, text);
 > +		b43warn(wl, "%s", text);
 >  }
would probably be better solved by doing

--- a/drivers/net/wireless/b43/main.c
+++ b/drivers/net/wireless/b43/main.c
@@ -1999,11 +1999,11 @@ static void b43_release_firmware(struct b43_wldev *dev)
 
 static void b43_print_fw_helptext(struct b43_wl *wl, bool error)
 {
-	const char *text;
+	static const char text[] =
+		"You must go to "
+		"http://linuxwireless.org/en/users/Drivers/b43#devicefirmware "
+		"and download the latest firmware (version 4).\n";
 
-	text = "You must go to "
-	       "http://linuxwireless.org/en/users/Drivers/b43#devicefirmware "
-	       "and download the latest firmware (version 4).\n";
 	if (error)
 		b43err(wl, text);
 	else

and in any case I'm not totally convinced that we want to add the bloat
for trivial cases like

	char *safe = "foo";
	printk(safe);

Would be nice to think of a cleverer way to handle that...

 - R.
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