[PATCH] SEGV in libsysfs/dlist.c

Hannes Reinecke

author

2004-03-18 12:15 UTC #0 lore raw

PATCH 1/1 SEGV in libsysfs/dlist.c

Hi all, Greg,

libsysfs/dlist.c: _dlist_mark_move()

is missing checks for empty lists and may (and indeed, does) crash when called with empty dlists.

Please apply.

Cheers,

Hannes

Signature · 4 lines

Dr. Hannes Reinecke			[email protected]
SuSE Linux AG				S390 & zSeries
Maxfeldstraße 5				+49 911 74053 688
90409 Nürnberg				http://www.suse.de

===== dlist.c 1.3 vs edited =====

dlist.c renamed from libsysfs/dlist.c +2 -2

@@ -74,14 +74,14 @@
 {
   if(direction)
     {
-      if( list->marker->next!=NULL)
+      if( list->marker && list->marker->next!=NULL)
 	list->marker=list->marker->next;
       else
 	return(NULL);
     }
   else
     {
-      if( list->marker->prev!=NULL)
+      if( list->marker && list->marker->prev!=NULL)
 	list->marker=list->marker->prev;
       else
 	return(NULL);

Greg KH

2004-03-24 23:15 UTC #1 lore raw

Quoted 6 lines · Hannes Reinecke

Hi all, Greg,
libsysfs/dlist.c: _dlist_mark_move()
is missing checks for empty lists and may (and indeed, does) crash when called with empty dlists.

What code causes this to happen? udev? If so, where?

thanks,

greg k-h

-------------------------------------------------------
This SF.Net email is sponsored by: IBM Linux Tutorials
Free Linux tutorial presented by Daniel Robbins, President and CEO of GenToo technologies. Learn everything from fundamentals to system administration.http://ads.osdn.com/?ad_id70&alloc_id638&op=click
_______________________________________________
Linux-hotplug-devel mailing list http://linux-hotplug.sourceforge.net
[email protected]
https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel

Ananth N Mavinakayanahalli

2004-03-25 04:32 UTC #2 lore raw

In reply to Hannes Reinecke

Quoted 10 lines · Greg KH

Quoted 6 lines · Hannes Reinecke
Hi all, Greg,
libsysfs/dlist.c: _dlist_mark_move()
is missing checks for empty lists and may (and indeed, does) crash when called with empty dlists.
What code causes this to happen? udev? If so, where?

When a "get" function is called for obtaining a list, (of say, attirbutes) it returns a NULL either because it was not able to retrieve the data from sysfs (in which case the errno is set appropriately) or if the list is NULL (because there are no elements exposed thru' sysfs), in which case the errno is "0". If the list is not checked to be NULL, there is a possibility of a de-referencing a NULL pointer.

Libsysfs takes care of this situation internally. With Dr. Hannes' patch, we do not have to bother of segfaulting even if a NULL is passed.

Thanks,
Ananth

-------------------------------------------------------
This SF.Net email is sponsored by: IBM Linux Tutorials
Free Linux tutorial presented by Daniel Robbins, President and CEO of GenToo technologies. Learn everything from fundamentals to system administration.http://ads.osdn.com/?ad_id70&alloc_id638&op=click
_______________________________________________
Linux-hotplug-devel mailing list http://linux-hotplug.sourceforge.net
[email protected]
https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel

Greg KH

Applied

2004-03-31 22:58 UTC #3 lore raw

In reply to Hannes Reinecke

Quoted 8 lines · Hannes Reinecke

Hi all, Greg,
libsysfs/dlist.c: _dlist_mark_move()
is missing checks for empty lists and may (and indeed, does) crash when called with empty dlists.
Please apply.

Applied, thanks.

greg k-h

-------------------------------------------------------
This SF.Net email is sponsored by: IBM Linux Tutorials
Free Linux tutorial presented by Daniel Robbins, President and CEO of GenToo technologies. Learn everything from fundamentals to system administration.http://ads.osdn.com/?ad_id70&alloc_id638&op=click
_______________________________________________
Linux-hotplug-devel mailing list http://linux-hotplug.sourceforge.net
[email protected]
https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel