The stack is frequently used for convenient temporary storage, because allocated memory is automatically freed when the function returns. Generally, the operating system will grow the stack as needed. However, this can fail due to a lack of memory or collision with other allocated areas of the address space (depending on the architecture). When this occurs, the operating system may terminate the program abnormally. This condition can be exploited to cause a denial-of-service attack in cases where an attacker can control or influence the amount of stack memory allocatedAvoid excessive stack allocations, particularly in situations where the growth of the stack can be controlled of influenced by an attacker.
Non-Compliant Code Example
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The stack space needed grows exponentially with respect to the parameter n. When tested on a Linux system, fib1(100) crashes with a segmentation faultLarge values of n have been shown to cause abnormal program termination.
Compliant Solution
This implementation of the Fibonacci functions eliminates the use of recursion.
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Because there is no recursion, the amount of stack space needed does not depend on the parameter n, greatly reducing the risk of stack overflow.
Risk Assessment
Stack overflow caused by excessive stack allocations or recursion could lead to abnormal termination and denial-of-service attacks.
use a large number of stack pages, possibly resulting in the process being killed due to lack of memory, or simply cause the stack pointer to point to a different region of memory. The latter could be used to write to an arbitrary memory location.Program stacks are frequently used for convenient temporary storage, because allocated memory is automatically freed when the function returns. Generally, the operating system will grow the stack as needed. However, growing the stack can fail due to a lack of memory or collision with other allocated areas of the address space (depending on the architecture). When the stack is exhausted, the operating system may terminate the program abnormally. This behavior can be exploited by an attacker to cause a denial-of-service attack in situations where the attacker can control or influence the amount of stack memory allocated.
Recommendation | Severity | Likelihood | Remediation Cost | Priority | Level |
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MEM05-A | 1 (low) | 1 (unlikely) | 2 (medium) | P2 | L3 |
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The Coverity Prevent STACK_USE checker can help detect single stack allocations that are dangerously large, although it will not detect excessive stack use resulting from recursion. Because Coverity Prevent cannot discover all violations of this rule so , further verification is necessary.
References
References
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\[[ISO/IEC 9899-1999|AA. C References#ISO/IEC 9899-1999]\] Section 6.7.5.2, "Array declarators", Section 7.20.3, "Memory management functions"
\[[Seacord 05|AA. C References#Seacord 05]\] Chapter 4, "Dynamic Memory Management"
\[[van Sprundel 06|http://ilja.netric.org/files/Unusual%20bugs.pdf]\] "Stack Overflow" |
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