BF Specification of CVE-2017-17833 SLPD Double Free in OpenSLP in v1.0.2 and v1.1.0
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Missing reposition of the 'result' pointer leads to a dangling pointer due to reallocation of the same object via 'sendbuf', which, when used to resize (second reallocation) the object leads to a Double Deallocate -- aka double free. If exploited, this can lead to a denial of service or an arbitrary (remote) code execution.
[openslp/slpd/slpd_process.c#L409](https://dumpco.re/blog/openslp-2.0.0-double-free https://sourceforge.net/p/openslp/mercurial/ci/151f07745901cbdba6e00e4889561b4083250da1/tree/openslp/slpd/slpd_process.c#l409)
vendor:product: openslp:openslp:1.0.2 |
| Class | Definition |
| MAD | Memory Addressing (MAD) class – The pointer to an object is initialized, repositioned, or reassigned to an improper memory address. |
| MMN | Memory Management (MMN) class – An object is allocated, deallocated, or resized improperly. |
| Operation | Definition |
| Reposition | Reposition operation – Change the pointer to another position inside its object. |
| Reallocate-Extend | Reallocate-Extend operation – Reserve a new larger piece of memory for an object at a new address, copy the object content there, reassign its pointer, and deallocate the previous piece of memory. |
| Cause/Consequence | Definition |
| Code Bug | Code 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 Code | Missing Code bug - The operation is entirely absent. |
| Address Error/Fault | Address Fault/Error type – The object address in use is wrong. |
| Dangling Pointer | Dangling Pointer fault/error – Still holds the address of its successfully deallocated object (e.g., pointer to a freed heap object or with a returned by a function stack object address). |
| Memory Corruption/Disclosure Final Error | Memory Corruption/Disclosure exploitable error type – An exploitable or undefined system behavior caused by memory addressing, allocation, use, and deallocation bugs. |
| Double Deallocate | Double Deallocate exploitable error – An attempt to deallocate a deallocated (freed) object or via an uninitialized pointer. |
| Operation Attribute | Definition |
| Mechanism | Mechanism operation attribute type – Shows how the buggy/faulty operation code is performed. |
| Sequential | Sequential operation attribute – The operation is via iterating over the object elements. |
| Explicit | Explicit operation attribute – The operation is via a function/method call. |
| Source Code | Source Code operation attribute type – Shows where the operation with the bug or a faulty operand is in the program – in what kind of software. |
| Third-Party | Third-Party operation attribute – The operation code is in a third-party software. |
| Execution Space | Execution Space operation attribute type – Shows where the buggy/faulty operation code is running or with what privilege level. |
| Userland | Userland operation attribute – The bugged code runs in an environment with privilege levels, but in unprivileged mode (e.g., ring 3 in x86 architecture). |
| Operand Attribute | Definition |
| Address State | Address State operand attribute type - State operand attribute type – Shows where the address is in the memory layout. |
| Heap | Heap operand attribute – The object is a dynamically allocated data structure (e.g., via malloc() and new). |
| Size Kind | Size Kind operand attribute type – Shows what the limit for traversal of the object is. |
| Used | Used operand attribute – A supplied size for an object. |