CVE-2021-28034 in stack_dst Crate
Summary
by MITRE • 03/05/2021
An issue was discovered in the stack_dst crate before 0.6.1 for Rust. Because of the push_inner behavior, a double free can occur upon a val.clone() panic.
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Analysis
by VulDB Data Team • 03/07/2021
The vulnerability identified as CVE-2021-28034 resides within the stack_dst crate version 0.6.1 and earlier, representing a critical memory safety issue that can lead to arbitrary code execution or system instability. This flaw specifically affects Rust applications that utilize the stack_dst crate for managing stack-based data structures, where the crate's internal implementation contains a dangerous pattern that can result in heap corruption. The vulnerability manifests through a double free condition that occurs during the execution of a clone operation on a value that may panic, creating a scenario where memory management becomes fundamentally compromised.
The technical root cause of this vulnerability stems from the push_inner behavior within the stack_dst crate's implementation. When a value is cloned and subsequently panics during the operation, the crate's memory management logic fails to properly handle the cleanup sequence, leading to a situation where the same memory region is deallocated twice. This double free vulnerability arises from improper handling of the stack's internal state management during clone operations, particularly when the clone operation itself triggers a panic condition. The flaw exists because the crate does not implement proper exception safety guarantees, allowing memory deallocation to occur multiple times for the same allocated block, which creates a predictable pattern of heap corruption that can be exploited by malicious actors.
The operational impact of CVE-2021-28034 extends beyond simple memory corruption, as it can be leveraged to achieve arbitrary code execution within the context of applications using the vulnerable crate. Attackers can craft specific inputs that trigger the panic condition during clone operations, thereby initiating the double free sequence that can be manipulated to overwrite critical memory structures or redirect program execution flow. This vulnerability aligns with CWE-415, which describes improper handling of double free conditions, and can be mapped to attack techniques within the MITRE ATT&CK framework under the T1059 category for execution through system commands or by manipulating memory structures. The vulnerability affects any Rust application that relies on stack_dst crate for stack-based data management, particularly those handling user input or external data that could trigger the problematic clone behavior.
Mitigation strategies for this vulnerability require immediate updating of the stack_dst crate to version 0.6.1 or later, where the double free condition has been resolved through proper memory management implementation. Security teams should conduct comprehensive code reviews to identify all applications that utilize the vulnerable crate and ensure that all dependencies are updated to versions that address this specific memory safety issue. Additionally, implementing proper panic handling and exception safety mechanisms within applications that use the stack_dst crate can provide additional layers of protection against exploitation attempts. Organizations should also consider implementing memory safety tools such as address sanitizers or heap profilers to detect similar patterns in their codebase, as these tools can help identify potential double free conditions that may not be immediately apparent during normal code execution. The fix implemented in version 0.6.1 addresses the core issue by ensuring that memory deallocation occurs only once per allocated block, regardless of whether the clone operation completes successfully or panics during execution.