BF Specification of CVE-2021-21834 Bad Alloc in GPAC v1.0.1

Missing verification on the range for the user-controlled 'nb_entries' ((u64)ptr->nb_entries * sizeof(u64) must not be greater than a 32-bit int) results in an inconsistent value, which becomes a wrong argument for the multiplication ‘*’ operator in 'ptr->nb_entries * sizeof(u64)' . The result wraps around (integer overflow on a 32-bit platform) and becomes a small number used to allocate not enough memory for the 'ptr->offsets[entries]' buffer, allowing a pointer reposition over its bounds, which, when used to write leads to a heap buffer overflow. If exploited, this can lead to denial of service (DOS) --availability loss, or arbitrary code execution (ACE) and more specificqlly remote code execution (RCE) -- everything could be lost.

vendor:product: gpac:gpac:1.0.1

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.
MADMemory Addressing (MAD) class – The pointer to an object is initialized, repositioned, or reassigned to an improper memory address.
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.
RepositionReposition operation – Change the pointer to another position inside its object.
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.
   Inconsistent ValueInconsistent Value fault/error – Data value does not correspond to the value of a related data (e.g., inconstancy between the value of a size variable and the actual buffer size).
   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.
Address Error/FaultAddress Fault/Error type – The object address in use is wrong.
   Over Bounds PointerOver Bounds Pointer fault/error – Holds an address above the upper boundary of its object.
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
MechanismMechanism operation attribute type – Shows how the buggy/faulty operation code is performed.
   RangeRange operation attribute – The operation checks data are within a (min, max) interval.
   OperatorOperator operation attribute – The operation is via a function with a symbolic name that implements a mathematical, relational or logical operation.
   ExplicitExplicit operation attribute – The operation is via a function/method call.
   SequentialSequential operation attribute – The operation is via iterating over the object elements.
Source CodeSource Code operation attribute type – Shows where the buggy/faulty operation code is in software or firmware.
   Third-PartyThird-Party operation attribute – The operation code is in a third-party software.
Execution SpaceExecution Space operation attribute type – Shows where the buggy/faulty operation code is running or with what privilege level.
   LocalLocal operation attribute – The bugged code runs in an environment with access control policy with limited (local user) permission.
   UserlandUserland operation attribute – The bugged code runs in an environment with privilege levels, but in unprivileged mode (e.g., ring 3 in x86 architecture).
Operand AttributeDefinition
Data StateData State operand attribute type operand attribute – Shows where the data come from.
   StoredStored operand attribute – Data are from a permanent storage (e.g., file, database on a storage device); they are at rest.
Name StateName State operand attribute type – Shows at what stage the entity name is.
   BoundBound operand attribute – The name is linked to a declared (or inferred) data type, a defined object's data, or a called function implementation.
Data KindData Kind operand attribute type – Shows what the data value is.
   NumericNumeric operand attribute – A number – a sequence of digits.
Type KindType Kind operand attribute type – Shows what the data type composition is.
   StructureStructure operand attribute – A composite data type - e.g., array, list, map, class. A structured data type is built from other data types and has primitive or structured members.
Address StateAddress State operand attribute type - Shows where the address is in the memory layout.
   HeapHeap operand attribute – The object is a dynamically allocated data structure (e.g., via malloc() and new).
Size KindSize Kind operand attribute type – Shows what the limit for traversal of the object is.
   UsedUsed operand attribute – A supplied size for an object.
Address KindAddress Kind operand attribute type - Shows what the accessed outside object's bounds memory is.
   HugeHuge operand attribute - More than 1 KB of memory.