Subject: [PATCH] isdnloop: fix and simplify isdnloop_init()

From: Fengguang Wu <[email-masked]>
Date: Thu, 2 Aug 2012 19:05:43 +0800

Fix a buffer overflow bug by removing the revision transform code.

[   22.016214] isdnloop-ISDN-driver Rev 1.11.6.7 
[   22.097508] isdnloop: (loop0) virtual card added
[   22.174400] Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: ffffffff83244972
[   22.174400] 
[   22.436157] Pid: 1, comm: swapper Not tainted 3.5.0-bisect-00018-gfa8bbb1-dirty #129
[   22.624071] Call Trace:
[   22.720558]  [<ffffffff832448c3>] ? CallcNew+0x56/0x56
[   22.815248]  [<ffffffff8222b623>] panic+0x110/0x329
[   22.914330]  [<ffffffff83244972>] ? isdnloop_init+0xaf/0xb1
[   23.014800]  [<ffffffff832448c3>] ? CallcNew+0x56/0x56
[   23.090763]  [<ffffffff8108e24b>] __stack_chk_fail+0x2b/0x30
[   23.185748]  [<ffffffff83244972>] isdnloop_init+0xaf/0xb1

Signed-off-by: Fengguang Wu <[email-masked]>
---
 drivers/isdn/isdnloop/isdnloop.c |   13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

--- linux.orig/drivers/isdn/isdnloop/isdnloop.c	2012-05-24 19:03:06.748430938 +0800
+++ linux/drivers/isdn/isdnloop/isdnloop.c	2012-08-02 11:57:16.806437909 +0800
@@ -16,7 +16,7 @@
 #include <linux/sched.h>
 #include "isdnloop.h"
 
-static char *revision = "$Revision: 1.11.6.7 $";
+static char *revision = "1.11.6.7";
 static char *isdnloop_id = "loop0";
 
 MODULE_DESCRIPTION("ISDN4Linux: Pseudo Driver that simulates an ISDN card");
@@ -1494,16 +1494,7 @@ isdnloop_addcard(char *id1)
 static int __init
 isdnloop_init(void)
 {
-	char *p;
-	char rev[10];
-
-	if ((p = strchr(revision, ':'))) {
-		strcpy(rev, p + 1);
-		p = strchr(rev, '$');
-		*p = 0;
-	} else
-		strcpy(rev, " ??? ");
-	printk(KERN_NOTICE "isdnloop-ISDN-driver Rev%s\n", rev);
+	printk(KERN_NOTICE "isdnloop-ISDN-driver Rev %s\n", revision);
 
 	if (isdnloop_id)
 		return (isdnloop_addcard(isdnloop_id));