[UNIX] Samba smbd Memory Exhaustion DoS



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Samba smbd Memory Exhaustion DoS
------------------------------------------------------------------------


SUMMARY

"The <http://www.samba.org/> smbd daemon maintains internal data
structures used track active connections to file and printer shares."

smbd may allow internal structures maintaining state for share connections
to grow unbounded.

DETAILS

Vulnerable Systems:
* Samba version 3.0.1 and above
* Samba version 3.0.22 and prior

In certain circumstances an attacker may be able to continually increase
the memory usage of an smbd process by issuing a large number of share
connection requests. This defect affects all Samba configurations.

CVE Information:
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2006-3403>
CAN-2006-3403

Vendor Status:
The vendor has issued a patch:
Index: source/smbd/service.c
-==================================================================
--- source/smbd/service.c (revision 16676)
+++ source/smbd/service.c (working copy)
@@ -763,6 +763,11 @@
smb_panic("make_connection: PANIC ERROR. Called as nonroot\n");
}

+ if (conn_num_open() > 2047) {
+ *status = NT_STATUS_INSUFF_SERVER_RESOURCES;
+ return NULL;
+ }
+
if(lp_security() != SEC_SHARE) {
vuser = get_valid_user_struct(vuid);
if (!vuser) {



ADDITIONAL INFORMATION

The information has been provided by <mailto:jerry@xxxxxxxxx> Gerald
(Jerry) Carter.
The original article can be found at:
<http://www.samba.org/samba/security/CAN-2006-3403.html>
http://www.samba.org/samba/security/CAN-2006-3403.html
The patch can be downloaded at:
<http://us4.samba.org/samba/ftp/patches/security/samba-3.0-CAN-2006-3403.patch> http://us4.samba.org/samba/ftp/patches/security/samba-3.0-CAN-2006-3403.patch



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