BF Specification of CVE-2007-6429 Integer overflows in X.Org Xserver before 1.4.1

Missing verifications of input values leads to use of a wrong argument in a memory size calculations and wraparounds , allowing allocation of not enough memory, which, when used leads to a buffer overflow. If exploited, this can lead to arbitrary code execution.

//generated// Missing Code to Verify in leads to Wrong Value

, which propagates to Wrong Argument Calculate in resulting in Wrap Around (integer overflow)

, which propagates to Wrong Size (in ‘xalloc()’ and ‘AshmFuncs()’) Allocate in resulting in Not Enough Memory

, which propagates to Not Enough Memory Write in resulting in Buffer Overflow

. If exploited this can lead to ACE (everything could be lost).


Bug Report

Code with Bug

Code with Fix

NVD Entry

DVRData Verification (DVR) class – Data are verified (semantics check) or corrected (assign, remove) improperly.
TCMType Computation (TCM) class – An arithmetic expression (over numbers, strings, or pointers) is calculated improperly, or a boolean condition is evaluated improperly.
MMNMemory Management (MMN) class – An object is allocated, deallocated, or resized improperly.
MUSMemory Use (MUS) class – An object is initialized, read, written, or cleared improperly.
VerifyVerify operation – Check data semantics (proper value/meaning) in order to accept (and possibly correct) or reject it.
CalculateCalculate operation – Find the result of a numeric, pointer, or string operation.
AllocateAllocate operation – Reserve space in memory for an object; defines its initial boundaries and size.
WriteWrite operation – Change the data value of an object to another meaningful value.
Code BugCode Bug type – Defect in the implementation of the operation – proper operands over an improper operation. A first cause for the chain of weaknesses underlying a software security vulnerability. Must be fixed to resolve the vulnerability.
   Missing CodeMissing Code bug - The operation is entirely absent.
Data Error/FaultData Fault/Error type – The object data has harmed semantics or inconsistent or wrong value.
   Wrong ValueWrong Value fault/error – The value of the data is not accurate (e.g., outside of a range).
   Wrong ArgumentWrong Argument fault/error – Inaccurate input data value, i.e., non-verified for harmed semantics.
   Wrap AroundWrap Around fault/error – A moved around-the-clock value over its data type upper or lower range, as it exceeds that range. (Integer Over-/Under-flow is a wrapped-around the upper/lower range integer value; may become very small/large and change to the opposite sign.
   Wrong SizeWrong Size fault/error – The value used as size does not match the actual size of the object (e.g., to restrict pointer repositioning or index increment/decrement in a repetition statement).
Size Error/FaultSize Fault/Error type – The object size in use is wrong.
   Not Enough MemoryNot Enough Memory fault/error – The allocated memory is too little for the data it should store.
Memory Corruption/Disclosure Final ErrorMemory Corruption/Disclosure exploitable error type – An exploitable or undefined system behavior caused by memory addressing, allocation, use, and deallocation bugs.
   Buffer OverflowBuffer Overflow exploitable error – Writing above the upper bound of an object – aka Buffer Over-Write.
Operation AttributeDefinition
Operand AttributeDefinition