Re: Memory Leak in Kpathsea

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In case I have correctly identified this as a memory leak, the simple
fix is to move the "free (cnf_files);" to just past the outermost
if-statement, i.e., to the end of the function body. This works
regardless of whether or not cnf_files is null because calling free
upon a null pointer is a no-op. For sake of completeness, I have
attached a patch for this simple fix.

On Mon, Jun 15, 2026 at 10:23=E2=80=AFPM Jonathan Gruber
<[email protected]> wrote:
>
> Hello.
>
> In the file Build/source/texk/kpathsea/cnf.c, in the function
> read_all_cnf, there appears to be a memory leak. If I understand
> correctly, the variable cnf_files, if nonnull, points to dynamically
> allocated memory. In the case that the expression cnf_files &&
> *cnf_files evaluates to true, i.e., when cnf_files is nonnull and
> *cnf_files is also nonnull, read_all_cnf eventually calls free upon
> cnf_files. Otherwise, i.e., either when cnf_files is null or when
> cnf_files is nonnull but *cnf_files is null, read_all_cnf never calls
> free upon cnf_files. As a result, when cnf_files is nonnull but
> *cnf_files is null, the memory pointed to by cnf_files is never freed,
> resulting in a memory leak. At least from my skimming of the source
> code of the function kpathsea_all_path_search, whose return value
> cnf_files is set to, it would be the case that cnf_files is nonnull
> while *cnf_files is null if cnf_files points to an empty list of
> strings.
>
> All my observations are based upon the latest version (at time of
> writing) of the trunk branch of TeX Live's Subversion repository.
>
> Thank you,
> Jonathan Gruber

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