Signedness error in the copy_from_read_buf function in n_tty.c for Linux kernel 2.6.10 and 2.6.11rc1 allows local users to read kernel memory via a negative argument.

Updated kernel packages that fix several security issues are now available for Red Hat Enterprise Linux 4.

This update has been rated as having important security impact by the Red Hat Security Response Team.

[Updated 9 August 2005] The advisory text has been updated to show that this update fixed the security issue named CVE-2005-0210 but not CVE-2005-0209. The issue CVE-2005-0209 was actually fixed by RHSA-2005:420. No changes have been made to the packages associated with this advisory.

The Linux kernel handles the basic functions of the operating system.

A flaw in the fib_seq_start function was discovered. A local user could use this flaw to cause a denial of service (system crash) via /proc/net/route. (CVE-2005-1041)

A flaw in the tmpfs file system was discovered. A local user could use this flaw to cause a denial of service (system crash). (CVE-2005-0977)

An integer overflow flaw was found when writing to a sysfs file. A local user could use this flaw to overwrite kernel memory, causing a denial of service (system crash) or arbitrary code execution.
(CVE-2005-0867)

Keith Owens reported a flaw in the Itanium unw_unwind_to_user function. A local user could use this flaw to cause a denial of service (system crash) on Itanium architectures. (CVE-2005-0135)

A flaw in the NFS client O_DIRECT error case handling was discovered.
A local user could use this flaw to cause a denial of service (system crash). (CVE-2005-0207)

A small memory leak when defragmenting local packets was discovered that affected the Linux 2.6 kernel netfilter subsystem. A local user could send a large number of carefully crafted fragments leading to memory exhaustion (CVE-2005-0210)

A flaw was discovered in the Linux PPP driver. On systems allowing remote users to connect to a server using ppp, a remote client could cause a denial of service (system crash). (CVE-2005-0384)

A flaw was discovered in the ext2 file system code. When a new directory is created, the ext2 block written to disk is not initialized, which could lead to an information leak if a disk image is made available to unprivileged users. (CVE-2005-0400)

A flaw in fragment queuing was discovered that affected the Linux kernel netfilter subsystem. On systems configured to filter or process network packets (e.g. firewalling), a remote attacker could send a carefully crafted set of fragmented packets to a machine and cause a denial of service (system crash). In order to sucessfully exploit this flaw, the attacker would need to know or guess some aspects of the firewall ruleset on the target system. (CVE-2005-0449)

A number of flaws were found in the Linux 2.6 kernel. A local user could use these flaws to read kernel memory or cause a denial of service (crash). (CVE-2005-0529, CVE-2005-0530, CVE-2005-0531)

An integer overflow in sys_epoll_wait in eventpoll.c was discovered. A local user could use this flaw to overwrite low kernel memory. This memory is usually unused, not usually resulting in a security consequence. (CVE-2005-0736)

A flaw when freeing a pointer in load_elf_library was discovered. A local user could potentially use this flaw to cause a denial of service (crash). (CVE-2005-0749)

A flaw was discovered in the bluetooth driver system. On systems where the bluetooth modules are loaded, a local user could use this flaw to gain elevated (root) privileges. (CVE-2005-0750)

A race condition was discovered that affected the Radeon DRI driver. A local user who has DRI privileges on a Radeon graphics card may be able to use this flaw to gain root privileges. (CVE-2005-0767)

Multiple range checking flaws were discovered in the iso9660 file system handler. An attacker could create a malicious file system image which would cause a denial or service or potentially execute arbitrary code if mounted. (CVE-2005-0815)

A flaw was discovered when setting line discipline on a serial tty. A local user may be able to use this flaw to inject mouse movements or keystrokes when another user is logged in. (CVE-2005-0839)

Red Hat Enterprise Linux 4 users are advised to upgrade their kernels to the packages associated with their machine architectures and configurations as listed in this erratum.

Please note that

A remote Denial of Service vulnerability was discovered in the Netfilter IP packet handler. This allowed a remote attacker to crash the machine by sending specially crafted IP packet fragments.
(CAN-2005-0209)

The Netfilter code also contained a memory leak. Certain locally generated packet fragments are reassembled twice, which caused a double allocation of a data structure. This could be locally exploited to crash the machine due to kernel memory exhaustion. (CAN-2005-0210)

Ben Martel and Stephen Blackheath found a remote Denial of Service vulnerability in the PPP driver. This allowed a malicious pppd client to crash the server machine. (CAN-2005-0384)

Georgi Guninski discovered a buffer overflow in the ATM driver. The atm_get_addr() function does not validate its arguments sufficiently, which could allow a local attacker to overwrite large portions of kernel memory by supplying a negative length argument. This could eventually lead to arbitrary code execution. (CAN-2005-0531)

Georgi Guninski also discovered three other integer comparison problems in the TTY layer, in the /proc interface and the ReiserFS driver. However, the previous Ubuntu security update (kernel version 2.6.8.1-16.11) already contained a patch which checks the arguments to these functions at a higher level and thus prevents these flaws from being exploited. (CAN-2005-0529, CAN-2005-0530, CAN-2005-0532)

Georgi Guninski discovered an integer overflow in the sys_epoll_wait() function which allowed local users to overwrite the first few kB of physical memory. However, very few applications actually use this space (dosemu is a notable exception), but potentially this could lead to privilege escalation. (CAN-2005-0736)

Eric Anholt discovered a race condition in the Radeon DRI driver. In some cases this allowed a local user with DRI privileges on a Radeon card to execute arbitrary code with root privileges.

Finally this update fixes a regression in the NFS server driver which was introduced in the previous security update (kernel version 2.6.8.1-16.11). We apologize for the inconvenience.
(https://bugzilla.ubuntulinux.org/show_bug.cgi?id=6749)

Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Multiple vulnerabilities in the Linux kernel have been discovered and fixed in this update. The following have been fixed in the 2.4 kernels :

Colin Percival discovered a vulnerability in Intel's Hyper-Threading technology could allow a local user to use a malicious thread to create covert channels, monitor the execution of other threads, and obtain sensitive information such as cryptographic keys via a timing attack on memory cache misses. This has been corrected by disabling HT support in all kernels (CVE-2005-0109).

When forwarding fragmented packets, a hardware assisted checksum could only be used once which could lead to a Denial of Service attack or crash by remote users (CVE-2005-0209).

A flaw in the Linux PPP driver was found where on systems allowing remote users to connect to a server via PPP, a remote client could cause a crash, resulting in a Denial of Service (CVE-2005-0384).

An information leak in the ext2 filesystem code was found where when a new directory is created, the ext2 block written to disk is not initialized (CVE-2005-0400).

A signedness error in the copy_from_read_buf function in n_tty.c allows local users to read kernel memory via a negative argument (CVE-2005-0530).

George Guninski discovered a buffer overflow in the ATM driver where the atm_get_addr() function does not validate its arguments sufficiently which could allow a local attacker to overwrite large portions of kernel memory by supplying a negative length argument.
This could potentially lead to the execution of arbitrary code (CVE-2005-0531).

A flaw when freeing a pointer in load_elf_library was found that could be abused by a local user to potentially crash the machine causing a Denial of Service (CVE-2005-0749).

A problem with the Bluetooth kernel stack in kernels 2.4.6 through 2.4.30-rc1 and 2.6 through 2.6.11.5 could be used by a local attacker to gain root access or crash the machine (CVE-2005-0750).

A race condition in the Radeon DRI driver allows a local user with DRI privileges to execute arbitrary code as root (CVE-2005-0767).

Paul Starzetz found an integer overflow in the ELF binary format loader's code dump function in kernels prior to and including 2.4.31-pre1 and 2.6.12-rc4. By creating and executing a specially crafted ELF executable, a local attacker could exploit this to execute arbitrary code with root and kernel privileges (CVE-2005-1263).

Multiple vulnerabilities in the Linux kernel have been discovered and fixed in this update. The following CVE names have been fixed in the LE2005 kernel :

Colin Percival discovered a vulnerability in Intel's Hyper-Threading technology could allow a local user to use a malicious thread to create covert channels, monitor the execution of other threads, and obtain sensitive information such as cryptographic keys via a timing attack on memory cache misses. This has been corrected by disabling HT support in all kernels (CVE-2005-0109).

An information leak in the ext2 filesystem code in kernels prior to 2.6.11.6 was found where when a new directory is created, the ext2 block written to disk is not initialized (CVE-2005-0400).

A flaw when freeing a pointer in load_elf_library was found in kernels prior to 2.6.11.6 that could be abused by a local user to potentially crash the machine causing a Denial of Service (CVE-2005-0749).

A problem with the Bluetooth kernel stack in kernels 2.4.6 through 2.4.30-rc1 and 2.6 through 2.6.11.5 could be used by a local attacker to gain root access or crash the machine (CVE-2005-0750).

Paul Starzetz found an integer overflow in the ELF binary format loader's code dump function in kernels prior to and including 2.4.31-pre1 and 2.6.12-rc4. By creating and executing a specially crafted ELF executable, a local attacker could exploit this to execute arbitrary code with root and kernel privileges (CVE-2005-1263).

The drivers for raw devices used the wrong function to pass arguments to the underlying block device in 2.6.x kernels. This made the kernel address space accessible to user-space applications allowing any local user with at least read access to a device in /dev/raw/* (usually only root) to execute arbitrary code with kernel privileges (CVE-2005-1264).

The it87 and via686a hardware monitor drivers in kernels prior to 2.6.11.8 and 2.6.12 prior to 2.6.12-rc2 created a sysfs file named 'alarms' with write permissions although they are not designed to be writable. This allowed a local user to crash the kernel by attempting to write to these files (CVE-2005-1369).

In addition to the above-noted CVE-2005-0109, CVE-2005-0400, CVE-2005-0749, CVE-2005-0750, and CVE-2005-1369 fixes, the following CVE names have been fixed in the 10.1 kernel :

The POSIX Capability Linux Security Module (LSM) for 2.6 kernels up to and including 2.6.8.1 did not properly handle the credentials of a process that is launched before the module is loaded, which could be used by local attackers to gain elevated privileges (CVE-2004-1337).

A flaw in the Linux PPP driver in kernel 2.6.8.1 was found where on systems allowing remote users to connect to a server via PPP, a remote client could cause a crash, resulting in a Denial of Service (CVE-2005-0384).

George Guninski discovered a buffer overflow in the ATM driver in kernels 2.6.10 and 2.6.11 before 2.6.11-rc4 where the atm_get_addr() function does not validate its arguments sufficiently which could allow a local attacker to overwrite large portions of kernel memory by supplying a negative length argument. This could potentially lead to the execution of arbitrary code (CVE-2005-0531).

The reiserfs_copy_from_user_to_file_region function in reiserfs/file.c before kernel 2.6.11, when running on 64-bit architectures, could allow local users to trigger a buffer overflow as a result of casting discrepancies between size_t and int data types. This could allow an attacker to overwrite kernel memory, crash the machine, or potentially obtain root access (CVE-2005-0532).

A race condition in the Radeon DRI driver in kernel 2.6.8.1 allows a local user with DRI privileges to execute arbitrary code as root (CVE-2005-0767).

Access was not restricted to the N_MOUSE discipline for a TTY in kernels prior to 2.6.11. This could allow local attackers to obtain elevated privileges by injecting mouse or keyboard events into other user's sessions (CVE-2005-0839).

Some futex functions in futex.c in 2.6 kernels performed get_user calls while holding the mmap_sem semaphore, which could allow a local attacker to cause a deadlock condition in do_page_fault by triggering get_user faults while another thread is executing mmap or other functions (CVE-2005-0937).

In addition to the above-noted CVE-2004-1337, CVE-2005-0109, CVE-2005-0384, CVE-2005-0400, CVE-2005-0531, CVE-2005-0532, CVE-2005-0749, CVE-2005-0750, CVE-2005-0767, CVE-2005-0839, CVE-2005-0937, CVE-2005-1263, CVE-2005-1264, and CVE-2005-1369 fixes, the following CVE names have been fixed in the 10.0/ Corporate 3.0 kernels :

A race condition in the setsid function in kernels before 2.6.8.1 could allow a local attacker to cause a Denial of Service and possibly access portions of kernel memory related to TTY changes, locking, and semaphores (CVE-2005-0178).

When forwarding fragmented packets in kernel 2.6.8.1, a hardware assisted checksum could only be used once which could lead to a Denial of Service attack or crash by remote users (CVE-2005-0209).

A signedness error in the copy_from_read_buf function in n_tty.c before kernel 2.6.11 allows local users to read kernel memory via a negative argument (CVE-2005-0530).

A vulnerability in the fib_seq_start() function allowed a local user to crash the system by readiung /proc/net/route in a certain way, causing a Denial of Service (CVE-2005-1041).

A vulnerability in the Direct Rendering Manager (DRM) driver in the 2.6 kernel does not properly check the DMA lock, which could allow remote attackers or local users to cause a Denial of Service (X Server crash) and possibly modify the video output (CVE-2004-1056).

The remote Redhat Enterprise Linux 4 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2005:366 advisory.

    The Linux kernel handles the basic functions of the operating system.

    A flaw in the fib_seq_start function was discovered. A local user could use     this flaw to cause a denial of service (system crash) via /proc/net/route.
    (CAN-2005-1041)

    A flaw in the tmpfs file system was discovered. A local user could use this     flaw to cause a denial of service (system crash). (CAN-2005-0977)

    An integer overflow flaw was found when writing to a sysfs file. A local     user could use this flaw to overwrite kernel memory, causing a denial of     service (system crash) or arbitrary code execution. (CAN-2005-0867)

    Keith Owens reported a flaw in the Itanium unw_unwind_to_user function. A     local user could use this flaw to cause a denial of service (system crash)     on Itanium architectures. (CAN-2005-0135)

    A flaw in the NFS client O_DIRECT error case handling was discovered. A     local user could use this flaw to cause a denial of service (system crash).
    (CAN-2005-0207)

    A small memory leak when defragmenting local packets was discovered that     affected the Linux 2.6 kernel netfilter subsystem.  A local user could send     a large number of carefully crafted fragments leading to memory exhaustion     (CAN-2005-0210)

    A flaw was discovered in the Linux PPP driver. On systems allowing remote     users to connect to a server using ppp, a remote client could cause a     denial of service (system crash). (CAN-2005-0384)

    A flaw was discovered in the ext2 file system code. When a new directory is     created, the ext2 block written to disk is not initialized, which could     lead to an information leak if a disk image is made available to     unprivileged users. (CAN-2005-0400)

    A flaw in fragment queuing was discovered that affected the Linux kernel     netfilter subsystem. On systems configured to filter or process network     packets (e.g. firewalling), a remote attacker could send a carefully     crafted set of fragmented packets to a machine and cause a denial of     service (system crash). In order to sucessfully exploit this flaw, the     attacker would need to know or guess some aspects of the firewall ruleset     on the target system. (CAN-2005-0449)

    A number of flaws were found in the Linux 2.6 kernel. A local user could     use these flaws to read kernel memory or cause a denial of service (crash).
    (CAN-2005-0529, CAN-2005-0530, CAN-2005-0531)

    An integer overflow in sys_epoll_wait in eventpoll.c was discovered. A     local user could use this flaw to overwrite low kernel memory. This memory     is usually unused, not usually resulting in a security consequence.
    (CAN-2005-0736)

    A flaw when freeing a pointer in load_elf_library was discovered. A local     user could potentially use this flaw to cause a denial of service (crash).
    (CAN-2005-0749)

    A flaw was discovered in the bluetooth driver system. On systems where the     bluetooth modules are loaded, a local user could use this flaw to gain     elevated (root) privileges. (CAN-2005-0750)

    A race condition was discovered that affected the Radeon DRI driver. A     local user who has DRI privileges on a Radeon graphics card may be able to     use this flaw to gain root privileges. (CAN-2005-0767)

    Multiple range checking flaws were discovered in the iso9660 file system     handler. An attacker could create a malicious file system image which would     cause a denial or service or potentially execute arbitrary code if mounted.
    (CAN-2005-0815)

    A flaw was discovered when setting line discipline on a serial tty. A local     user may be able to use this flaw to inject mouse movements or keystrokes     when another user is logged in. (CAN-2005-0839)

    Red Hat Enterprise Linux 4 users are advised to upgrade their kernels     to the packages associated with their machine architectures and     configurations as listed in this erratum.

    Please note that

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote host is missing the patch for the advisory SUSE-SA:2005:018 (kernel).


The Linux kernel is the core component of the Linux system.

Several vulnerabilities were reported in the last few weeks which are fixed by this update.

The remote CentOS system is missing a security update which has been documented in Red Hat advisory RHSA-2005-366.

ID	Name	Product	Family	Severity
21928	CentOS 3 / 4 : kernel (CESA-2005:366)	Nessus	CentOS Local Security Checks	high
20721	Ubuntu 4.10 : linux-source-2.6.8.1 vulnerabilities (USN-95-1)	Nessus	Ubuntu Local Security Checks	high
18599	Mandrake Linux Security Advisory : kernel-2.4 (MDKSA-2005:111)	Nessus	Mandriva Local Security Checks	high
18598	Mandrake Linux Security Advisory : kernel (MDKSA-2005:110)	Nessus	Mandriva Local Security Checks	high
18095	RHEL 4 : kernel (RHSA-2005:366)	Nessus	Red Hat Local Security Checks	high
17617	SUSE-SA:2005:018: kernel	Nessus	SuSE Local Security Checks	high
801406	CentOS RHSA-2005-366 Security Check	Log Correlation Engine	Generic	high

Detections

Analytics

CVE-2005-0530

medium

Tenable Plugins

high

high

high

high

high

high

high