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Vulnerability of Linux kernel: signal sending

Synthesis of the vulnerability 

In some cases, a local attacker can send a signal to some processes.
Vulnerable software: Debian, Fedora, Linux, Mandriva Linux, NLD, OES, openSUSE, RHEL, SLES, ESX, ESXi, VMware Server, vCenter Server, VirtualCenter.
Severity of this announce: 1/4.
Creation date: 07/04/2009.
Références of this computer vulnerability: BID-34405, CERTA-2002-AVI-235, CVE-2009-1337, DSA-1787-1, DSA-1794-1, DSA-1800-1, FEDORA-2009-5356, FEDORA-2009-5383, MDVSA-2009:119, MDVSA-2009:135, RHSA-2009:0451-02, RHSA-2009:0473-01, RHSA-2009:1024-01, RHSA-2009:1077-01, RHSA-2009:1550-01, SUSE-SA:2009:028, SUSE-SA:2009:030, SUSE-SA:2009:031, SUSE-SA:2009:032, SUSE-SA:2009:033, SUSE-SU-2011:0928-1, VIGILANCE-VUL-8605, VMSA-2009-0016, VMSA-2009-0016.1, VMSA-2009-0016.2, VMSA-2009-0016.3, VMSA-2009-0016.4, VMSA-2009-0016.5, VMSA-2010-0010.

Description of the vulnerability 

When a process ends, it sends a SIGCHLD signal to its parent. When a thread ends, it can send a signal to the process. These two features store the signal number in the exit_signal field of the task_struct structure.

The exit_notify() function of the kernel/exit.c file ensures that the value of exit_signal is SIGCHLD, when the process ends. However, if the process ends with the CAP_KILL capability, the value previously stored in exit_signal is left untouched. This case occurs when the process calls an exec() on a suid program.

In this case, the signal sent by the last thread is thus sent to the parent process.
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This computer threat note impacts software or systems such as Debian, Fedora, Linux, Mandriva Linux, NLD, OES, openSUSE, RHEL, SLES, ESX, ESXi, VMware Server, vCenter Server, VirtualCenter.

Our Vigil@nce team determined that the severity of this weakness alert is low.

The trust level is of type confirmed by the editor, with an origin of user shell.

A proof of concept or an attack tool is available, so your teams have to process this alert. An attacker with a specialist ability can exploit this computer weakness note.

Solutions for this threat 

Linux kernel: version 2.6.30.
Version 2.6.30 is corrected:
  ftp://ftp.kernel.org/pub/linux/kernel/v2.6/

Linux kernel: version 2.6.29.3.
Version 2.6.29.3 is corrected:
  http://www.kernel.org/pub/linux/kernel/v2.6/

Linux kernel: version 2.6.28.10.
Version 2.6.28.10 is corrected:
  http://www.kernel.org/pub/linux/kernel/v2.6/

Linux kernel: version 2.6.27.22.
Version 2.6.27.22 is corrected:
  http://www.kernel.org/pub/linux/kernel/v2.6/

Linux kernel: version 2.4.37.1.
Version 2.4.37.1 is corrected:
  http://www.kernel.org/pub/linux/kernel/v2.4/

VMware ESX, ESXi, VirtualCenter: solution.
Following version is corrected:
VirtualCenter 4.0 Update 1
  http://downloads.vmware.com/download/download.do?downloadGroup=VC40U1
VMware Virtual Center 2.5 Update 6
  http://downloads.vmware.com/download/download.do?downloadGroup=VC250U6
ESXi 4.0 Update 1
  https://hostupdate.vmware.com/software/VUM/OFFLINE/release-155-20091116-013169/ESXi-4.0.0-update01.zip
ESXi 3.5
  http://download3.vmware.com/software/vi/ESXe350-201002401-O-SG.zip
ESX 4.0 Update 1
  https://hostupdate.vmware.com/software/VUM/OFFLINE/release-158-20091118-187517/ESX-4.0.0-update01.zip
  known problems: http://kb.vmware.com/kb/1016070
ESX 3.5
  http://download3.vmware.com/software/vi/ESX350-201002407-SG.zip
  http://download3.vmware.com/software/vi/ESX350-201002402-SG.zip
  http://download3.vmware.com/software/vi/ESX350-201002404-SG.zip
  http://download3.vmware.com/software/vi/ESX350-201003403-SG.zip
ESX 3.0.3
  http://download3.vmware.com/software/vi/ESX303-201002204-UG.zip
  http://download3.vmware.com/software/vi/ESX303-201002206-UG.zip
  http://download3.vmware.com/software/vi/ESX303-201002205-UG.zip

Linux kernel: patch for signal.
A patch is available in information sources.

Debian 4: new linux-2.6.24 packages.
New packages are available:
  http://security.debian.org/pool/updates/main/l/linux-2.6.24/linux-*-2.6.24_2.6.24-6~etchnhalf.8etch1_*.deb

Debian 4: new linux-2.6 packages.
New packages are available:
  http://security.debian.org/pool/updates/main/l/linux-2.6/*_2.6.18.dfsg.1-24etch1_*.deb

Debian 5: new linux-2.6 packages.
New packages are available:
  http://security.debian.org/pool/updates/main/l/linux-2.6/*-2.6.26_2.6.26-15lenny2_*.deb

Fedora: new kernel packages (26/05/2009).
New packages are available:
  kernel-2.6.27.24-78.2.53.fc9
  kernel-2.6.27.24-170.2.68.fc10

Mandriva 2009.1: new kernel packages.
New packages are available:
Mandriva Linux 2009.1:
  kernel-2.6.29.3-1mnb2

Mandriva: new kernel packages.
New packages are available:
  Mandriva Linux 2009.0: kernel-2.6.27.24-1mnb2

openSUSE 10.3: new kernel packages.
New packages are available:
  http://download.opensuse.org/update/10.3/rpm/*/kernel-*-2.6.22.19-0.3.*.rpm

openSUSE 11.0: new kernel packages.
New packages are available:
  http://download.opensuse.org/update/11.0/rpm/*/kernel-*-2.6.25.20-0.4.*.rpm

openSUSE 11.1, SLE 11: new kernel packages.
New packages are available.

RHEL 3: new kernel packages.
New packages are available:
  kernel-2.4.21-63.EL

RHEL 4.7: new kernel packages.
New packages are available:
  kernel-2.6.9-78.0.24.EL

RHEL 4.8: new kernel packages.
New packages are available:
Red Hat Enterprise Linux version 4: kernel-2.6.9-89.EL

RHEL 5 MRG: new kernel-rt packages.
New packages are available:
MRG Realtime for RHEL 5 Server:
  kernel-rt-2.6.24.7-111.el5rt

RHEL 5: new kernel packages.
New packages are available:
  kernel-2.6.18-128.1.10.el5

SUSE 9: new kernel packages.
New packages are available.

SUSE LE 9: new kernel packages (23/08/2011).
New packages are available:
http://download.novell.com/patch/finder/?keywords=c05dae2ea95bb787f18166cf12f585e3

SUSE: new kernel packages.
New packages are available, as indicated in information sources.

VMware ESX 3.5: patch ESX350-201006401-SG.
A patch is available:
  http://download3.vmware.com/software/vi/ESX350-201006401-SG.zip
  md5sum: b89fb8a51c4a896bc0bf297b57645d1d
  http://kb.vmware.com/kb/1022899
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