svn commit: r241003 - stable/9/usr.sbin/bsnmpd/modules/snmp_hostres

[Mikolaj Golub]

Author: trociny
Date: Thu Sep 27 18:51:03 2012
New Revision: 241003
URL: http://svn.freebsd.org/changeset/base/241003

Log:
  MFC r240595:
  
  In snmp_hostres, device_map table is used for consistent device table
  indexing. When a device has gone it is not removed from device_map
  table but just its entry_p field is set to NULL.
  
  So when traversing device_map in disk_OS_get_ATA_disks() and
  disk_OS_get_MD_disks() check for entry_p being NULL, otherwise the
  bsnmpd crash is possible when a removed map entry is dereferenced.
  
  Before the fix, for disk_OS_get_ATA_disks() the crash could be easily
  reproduced running:
  
    atacontrol detach ata1
  
  The crash was not observed in disk_OS_get_MD_disks() because currently
  snmp_hostres does no see md(4) disks: to get the device list it uses
  devinfo(3), which does not return md devices.
  
  Reported by:  Miroslav Lachman 000.fbsd quip.cz

Modified:
  stable/9/usr.sbin/bsnmpd/modules/snmp_hostres/hostres_diskstorage_tbl.c
Directory Properties:
  stable/9/usr.sbin/bsnmpd/   (props changed)

Modified: stable/9/usr.sbin/bsnmpd/modules/snmp_hostres/hostres_diskstorage_tbl.c
==============================================================================
--- stable/9/usr.sbin/bsnmpd/modules/snmp_hostres/hostres_diskstorage_tbl.c	Thu Sep 27 18:15:01 2012	(r241002)
+++ stable/9/usr.sbin/bsnmpd/modules/snmp_hostres/hostres_diskstorage_tbl.c	Thu Sep 27 18:51:03 2012	(r241003)
@@ -287,6 +287,9 @@ disk_OS_get_ATA_disks(void)
 
 	/* Walk over the device table looking for ata disks */
 	STAILQ_FOREACH(map, &device_map, link) {
+		/* Skip deleted entries. */
+		if (map->entry_p == NULL)
+			continue;
 		for (found = lookup; found->media != DSM_UNKNOWN; found++) {
 			if (strncmp(map->name_key, found->dev_name,
 			    strlen(found->dev_name)) != 0)
@@ -345,6 +348,9 @@ disk_OS_get_MD_disks(void)
 
 	/* Look for md devices */
 	STAILQ_FOREACH(map, &device_map, link) {
+		/* Skip deleted entries. */
+		if (map->entry_p == NULL)
+			continue;
 		if (sscanf(map->name_key, "md%d", &unit) != 1)
 			continue;