Re: [PATCH v2] isdnloop: fix and simplify isdnloop_init()

From: Karsten Keil
Date: Fri Aug 03 2012 - 04:48:22 EST


Am 03.08.2012 09:32, schrieb Fengguang Wu:
> On Thu, Aug 02, 2012 at 04:21:56PM -0700, David Miller wrote:
>> From: Fengguang Wu <fengguang.wu@xxxxxxxxx>
>> 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 <fengguang.wu@xxxxxxxxx>
>>
>> The reason the "$Revision ..." prefix is there is so that automated
>> version control tools will change the string automatically when code
>> is committed in CVS.
>>
>> In the GIT era this revision style is obsolete.
>>
>> Therefore you might as well just delete this crap altogether.
>
> OK. The below updated version will simply print the hard coded
> revision number as it's unlikely to change any more.
>
> Thanks,
> Fengguang
> ---
> isdnloop: fix and simplify isdnloop_init
>
> Fix a buffer overflow bug by hard coding the revision number.
>
> [ 22.016214] isdnloop-ISDN-driver Rev 1.11.6.7
> [ 22.097508] isdnloop: (loop0) virtual card added
> [ 22.174400] Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: ffffffff83244972
> [ 22.174400]
> [ 22.436157] Pid: 1, comm: swapper Not tainted 3.5.0-bisect-00018-gfa8bbb1-dirty #129
> [ 22.624071] Call Trace:
> [ 22.720558] [<ffffffff832448c3>] ? CallcNew+0x56/0x56
> [ 22.815248] [<ffffffff8222b623>] panic+0x110/0x329
> [ 22.914330] [<ffffffff83244972>] ? isdnloop_init+0xaf/0xb1
> [ 23.014800] [<ffffffff832448c3>] ? CallcNew+0x56/0x56
> [ 23.090763] [<ffffffff8108e24b>] __stack_chk_fail+0x2b/0x30
> [ 23.185748] [<ffffffff83244972>] isdnloop_init+0xaf/0xb1
>
> Signed-off-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>
> ---
> drivers/isdn/isdnloop/isdnloop.c | 12 +-----------
> 1 file changed, 1 insertion(+), 11 deletions(-)
>
> --- linux.orig/drivers/isdn/isdnloop/isdnloop.c 2012-08-03 15:24:49.047544323 +0800
> +++ linux/drivers/isdn/isdnloop/isdnloop.c 2012-08-03 15:27:39.503548375 +0800
> @@ -16,7 +16,6 @@
> #include <linux/sched.h>
> #include "isdnloop.h"
>
> -static char *revision = "$Revision: 1.11.6.7 $";
> static char *isdnloop_id = "loop0";
>
> MODULE_DESCRIPTION("ISDN4Linux: Pseudo Driver that simulates an ISDN card");
> @@ -1494,16 +1493,7 @@ isdnloop_addcard(char *id1)
> static int __init
> isdnloop_init(void)
> {
> - char *p;
> - char rev[10];
> -
> - if ((p = strchr(revision, ':'))) {
> - strcpy(rev, p + 1);
> - p = strchr(rev, '$');
> - *p = 0;
> - } else
> - strcpy(rev, " ??? ");
> - printk(KERN_NOTICE "isdnloop-ISDN-driver Rev%s\n", rev);
> + printk(KERN_NOTICE "isdnloop-ISDN-driver Rev 1.11.6.7\n");
>
> if (isdnloop_id)
> return (isdnloop_addcard(isdnloop_id));
>
>
You could remove the revision completely, even from the printk.
Maybe use pr_notice("isdnloop-ISDN driver loaded\n");

Best Regards
Karsten


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