Use of a Non-reentrant Function in a Concurrent Context

The product calls a non-reentrant function in a concurrent context in which a competing code sequence (e.g. thread or signal handler) may have an opportunity to call the same function or otherwise influence its state.


The following examples help to illustrate the nature of this weakness and describe methods or techniques which can be used to mitigate the risk.

Note that the examples here are by no means exhaustive and any given weakness may have many subtle varieties, each of which may require different detection methods or runtime controls.

Example One

In this example, a signal handler uses syslog() to log a message:

char *message;
void sh(int dummy) {
int main(int argc,char* argv[]) {
If the execution of the first call to the signal handler is suspended after invoking syslog(), and the signal handler is called a second time, the memory allocated by syslog() enters an undefined, and possibly, exploitable state.

Example Two

The following code relies on getlogin() to determine whether or not a user is trusted. It is easily subverted.

pwd = getpwnam(getlogin());
if (isTrustedGroup(pwd->pw_gid)) {
} else {

See Also

Comprehensive Categorization: Concurrency

Weaknesses in this category are related to concurrency.

SFP Secondary Cluster: Missing Lock

This category identifies Software Fault Patterns (SFPs) within the Missing Lock cluster (SFP19).

Concurrency Issues

Weaknesses in this category are related to concurrent use of shared resources.

Comprehensive CWE Dictionary

This view (slice) covers all the elements in CWE.

Weaknesses Introduced During Implementation

This view (slice) lists weaknesses that can be introduced during implementation.

Weakness Base Elements

This view (slice) displays only weakness base elements.

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