Fix potential 'use-after-free' by Admin 'SHOW PROCESSLIST' (PgSQL)#5182
Fix potential 'use-after-free' by Admin 'SHOW PROCESSLIST' (PgSQL)#5182renecannao merged 2 commits intov3.0from
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Accesses by 'stats___pgsql_processlist' to 'myconn->query.ptr' could lead to invalid memory accesses, as the pointed query could already have been free by the session after being issued.
As per the GCC manual, calls to 'strn*' function family shall be replaced by 'memcpy' when truncation (no null termination) is expected.
Summary of ChangesHello @JavierJF, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed! This pull request implements a critical memory safety fix for the Highlights
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Can one of the admins verify this patch? |
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Code Review
This pull request addresses a potential use-after-free vulnerability in SHOW PROCESSLIST for PostgreSQL sessions by changing how the current query is retrieved. Instead of accessing it through a potentially stale backend connection pointer, it now safely uses the session's CurrentQuery object. This is a solid improvement that enhances stability.
Additionally, the PR replaces a strncpy call with memcpy for safer handling of query strings that may not be null-terminated. I've pointed out an area where this improvement could be extended for consistency and to prevent potential truncation issues.
| memcpy(res, query_ptr, query_len - 3); | ||
| memcpy(res + (query_len - 3), "...", 3); | ||
| } else { | ||
| strncpy(res, query_ptr, query_len); |
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For consistency and correctness, this strncpy should also be replaced with memcpy, similar to the change in the if (trunc_query) block. The buffer pointed to by query_ptr is not guaranteed to be a null-terminated C-string and may contain embedded null characters. strncpy would stop at the first null character, leading to an incorrectly truncated query. Using memcpy ensures that the specified number of bytes are copied, preserving the integrity of the query string.
memcpy(res, query_ptr, query_len);
Description
This PR addresses the same issue as #5180 but for
PgSQL_Sessionand offers the same solution.