fix: free intervention.url on redirect path and check ngx_list_push r…#378
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eilandert wants to merge 1 commit into
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fix: free intervention.url on redirect path and check ngx_list_push r…#378eilandert wants to merge 1 commit into
eilandert wants to merge 1 commit into
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…eturn When ModSecurity fires a redirect intervention, intervention.url is allocated by msc_intervention() and must be freed by the caller. Previously it was leaked on every redirect, causing unbounded memory growth on busy servers using redirect-based rules. Additionally, the ngx_list_push() call was not checked for NULL before dereferencing the returned pointer, which would cause a worker crash under out-of-memory conditions. Fixes: - Add free(intervention.url) before returning the redirect status code - Add NULL check for ngx_list_push() return; free url and return 500 on allocation failure Severity: Critical (memory leak) / Medium (NULL deref) Reported-by: Security audit 2026-05-13
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thanks for the PR - do you think it would be possible to add some tests to check this feature? |
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Pull request overview
This PR addresses two issues in ngx_http_modsecurity_process_intervention: a memory leak of intervention.url on the redirect path, and a missing NULL check on the ngx_list_push() return value that could cause a worker crash under OOM.
Changes:
- Add
free(intervention.url)before returning on the redirect path. - Add a NULL check after
ngx_list_push()and free the URL before returningNGX_HTTP_INTERNAL_SERVER_ERROR.
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| free(intervention.url); | ||
| intervention.url = NULL; |
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…eturn
When ModSecurity fires a redirect intervention, intervention.url is allocated by msc_intervention() and must be freed by the caller. Previously it was leaked on every redirect, causing unbounded memory growth on busy servers using redirect-based rules.
Additionally, the ngx_list_push() call was not checked for NULL before dereferencing the returned pointer, which would cause a worker crash under out-of-memory conditions.
Fixes: