CVE-2007-3731
Description
From CVE.org
The Linux kernel 2.6.20 and 2.6.21 does not properly handle an invalid LDT segment selector in %cs (the xcs field) during ptrace single-step operations, which allows local users to cause a denial of service (NULL dereference and OOPS) via certain code that makes ptrace PTRACE_SETREGS and PTRACE_SINGLESTEP requests, related to the TRACE_IRQS_ON function, and possibly related to the arch_ptrace function.
Statement
This issue did not affect the versions of the Linux kernel as shipped with Red Hat Enterprise Linux 2.1, 3, or 4.
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
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