Security Vulnerability in Solaris NFSv4 Kernel Module May Panic an NFSv4 Client System

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Security Vulnerability in Solaris NFSv4 Kernel Module May Panic an NFSv4 Client System

1. Impact

A security vulnerability in the Solaris NFSv4 kernel module may allow a local unprivileged user to panic an NFSv4 client system, thereby leading to a Denial of Service (DoS) condition.

2. Contributing Factors

SPARC Platform

• Solaris 10 with patch 139466-02 or later and without patch 141733-03
• OpenSolaris based upon builds snv_102 through snv_119

x86 Platform

• Solaris 10 with patch 139467-02 or later and without patch 141734-03
• OpenSolaris based upon builds snv_102 through snv_119

Notes:

1. Solaris 8 and 9 are not impacted by this issue

2. Only those systems which have NFSv4 mounted file systems are impacted by this issue.

To determine if a system has NFSv4 mounted file systems, the following command may be executed:

$ nfsstat -m | grep "vers=4"
Flags: vers=4,proto=tcp,sec=sys,hard,intr,link,symlink,acl,rsize=1048576,wsize=1048576,retrans=5,timeo=600

NFSv4 mounted file systems include a "vers=4" field in the output of the nfsstat(1M) command.

3. OpenSolaris distributions may include additional bug fixes above and beyond the build from which it was derived. The base build can be derived as follows:

$ uname -v
snv_101

3. Symptoms

Should the described issue occur, the NFSv4 client system may panic with a stack trace similar to the following:

unix:die()
unix:trap()
unix:ktl0()
nfs:fn_move()
nfs:nfs4rename_persistent_fh()
nfs:nfs4rename()
genunix:fop_rename()
genunix:vn_renameat()
genunix:rename()

4. Workaround

To avoid this issue, use NFSv3 instead of NFSv4. The NFS client system can be configured not to use NFSv4 by setting NFS_CLIENT_VERSMAX=3 in /etc/default/nfs. Please refer to nfs(4) documentation.

5. Resolution

This issue is addressed in the following releases:

SPARC Platform

• Solaris 10 with patch 141733-03 or later
• OpenSolaris based upon builds snv_120 or later

x86 Platform

• Solaris 10 with patch 141734-03 or later
• OpenSolaris based upon builds snv_120 or later

For more information on Security Sun Alerts, see Technical Instruction ID 213557.

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