Fix memory leak and segfault from out-of-order NC file closure - #888
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bmribler wants to merge 2 commits into
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Fix memory leak and segfault from out-of-order NC file closure#888bmribler wants to merge 2 commits into
bmribler wants to merge 2 commits into
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_curr_opened and _ncdf track open files but diverge when files are closed out of order: _curr_opened correctly reaches 0, while _ncdf (high-water mark of _cdfs) does not. A prior fix changed the teardown check from `_curr_opened == 0` to `_ncdf == 0`, which then never fired in this case, leaking the _cdfs allocation (81,896 bytes) and leaving stale handles that bypassed validation and caused an out-of-bounds access / segfault on reuse. - Revert ncclose/ncabort to check `_curr_opened == 0` - Reset _ncdf and _curr_opened to 0 in ncreset_cdflist on teardown
bmribler
requested review from
brtnfld,
byrnHDF,
derobins,
fortnern,
glennsong09,
jhendersonHDF,
lrknox,
mattjala,
schwehr and
vchoi-hdfgroup
as code owners
August 1, 2026 03:47
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When opened files were closed in different order than when they were created, segfault and memory leaks occurred.
The global variables
static int _curr_opened = 0;/* the number of files currently opened */static int _ncdf = 0;/* high water mark on open cdf's */are used to track open files, but they diverge under out-of-order closure:
_curr_openedcorrectly drops to0, while_ncdfdoes not. A prior memory leak fix changed the teardown check from_curr_opened == 0to_ncdf == 0, so teardownnever fires in this case — leaking the
_cdfsallocation and leaving stale handles that skip validation, causing a segfault later.This PR reverts the previous change to check
_curr_opened == 0and resets_ncdfand_curr_openedto 0 inncreset_cdfliston teardown, which would have been correct in the previous fix.The fix has been verified with an out-of-order LIFO file-closure program under Valgrind.