BF Specification of CVE-2021-21834
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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 or arbitrary (remote) code execution.
| vendor:product: gpac:gpac:1.0.1 | Bug Report | Code with Bug | Code with Fix | NVD Entry |
| Class | Definition |
| DVR | Data are verified (semantics check) or corrected (assign, remove) improperly. |
| TCM | An arithmetic expression (over numbers, strings, or pointers) is calculated improperly, or a boolean condition is evaluated improperly. |
| MMN | An object is allocated, deallocated, or resized improperly. |
| MAD | The pointer to an object is initialized, repositioned, or reassigned to an improper memory address. |
| MUS | An object is initialized, read, written, or cleared improperly. |
| Operation | Definition |
| Verify | Check data semantics (proper value/meaning) in order to accept (and possibly correct) or reject it. |
| Calculate | Find the result of a numeric, pointer, or string operation. |
| Allocate | Reserve space in memory for an object; defines its initial boundaries and size. |
| Reposition | Change the pointer to another position inside its object. |
| Write | Change the data value of an object to another meaningful value. |
| Cause/Consequence | Definition |
| Code Defect Bug | The operation has a bug, which is the first cause for the chain of weaknesses underlying a software security vulnerability. The bug must be fixed to resolve the vulnerability. |
| Missing Code | The entire operation implementation or a part of its specification is absent. |
| Data Error/Fault | The object data has harmed semantics or inconsistent or wrong value |
| Inconsistent Value | 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 Argument | Inaccurate input data value, i.e., non-verified for harmed semantics. |
| Wrap Around | 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 Size | The value used as size does not match the actual size of the object. |
| Size Error/Fault | The object size in use is wrong. |
| Not Enough Memory | The allocated memory is too little for the data it should store. |
| Address Error/Fault | The object address in use is wrong. |
| Over Bounds Pointer | Points above the upper boundary of its object. |
| Memory Corruption/Disclosure Final Error | An exploitable or undefined system behavior caused by memory addressing, allocation, use, and deallocation bugs. |
| Buffer Overflow | Writes above the upper bound of an object -- aka Buffer Over-Write. |
| Operation Attribute | Definition |
| Mechanism | Shows how the buggy/faulty operation code is performed. |
| Range | Checking data are within a (min, max) interval. |
| Operator | A function with a symbolic name that implements a mathematical, relational or logical operation. |
| Explicit | The operation is performed by a function/method call. |
| Sequential | The operation is performed after iterating over the object elements. |
| Source Code | Shows where the buggy/faulty operation code is in the program -- in what kind of software. |
| Third-Party | The operation is in a third-party software. |
| Execution Space | Shows where the buggy/faulty operation code is running or with what privilege level). |
| Local | The bugged code runs in an environment with access control policy with limited (local user) permission. |
| Userland | The bugged code runs in an environment with privilege levels, but in unprivileged mode (e.g., ring 3 in x86 architecture). |
| Operand Attribute | Definition |
| Data State | Shows where the data come from. |
| Stored | The data are from a permanent storage (e.g., file, database on a storage device). |
| Name State | Shows at what stage the entity name is. |
| Bound | The name is linked to a declared (or inferred) data type, a defined object's data, or a called function implementation. |
| Data Kind | Shows what the data value is. |
| Numeric | A number -- a sequence of digits. |
| Type Kind | Shows what the data type composition is. |
| Structure | 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 State | Shows where the address is in the memory layout. |
| Heap | The object is a dynamically allocated data structure (e.g., via malloc() and new). |
| Size Kind | Shows what the limit for traversal of the object is. |
| Used | A supplied size for an object. |