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Fix Heap UAF in cupsdContinueJob via Concurrent Filter Deletion #1683

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Fix Heap UAF in cupsdContinueJob via Concurrent Filter Deletion #1683

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22 changes: 22 additions & 0 deletions scheduler/job.c
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Original file line number Diff line number Diff line change
Expand Up @@ -700,6 +700,28 @@ cupsdContinueJob(cupsd_job_t *job) /* I - Job */
cupsRWUnlock(&MimeLock);
}

/*
* Deep-copy the borrowed mime_filter_t pointers before dropping the
* lock: create_local_bg_thread() may concurrently call
* cupsdSetPrinterAttrs() -> delete_printer_filters() ->
* mimeDeleteFilter(), which free()s these objects while we are still
* holding raw pointers in 'filters'.
*/
if (filters)
{
cups_array_t *owned = cupsArrayNew3(NULL, NULL, NULL, 0, NULL,
(cups_afree_func_t)free);
for (filter = (mime_filter_t *)cupsArrayFirst(filters);
filter;
filter = (mime_filter_t *)cupsArrayNext(filters))
{
mime_filter_t *copy = calloc(1, sizeof(mime_filter_t));
if (copy) { *copy = *filter; cupsArrayAdd(owned, copy); }
}
cupsArrayDelete(filters);
filters = owned;
}

/*
* Set a minimum cost of 100 for all jobs so that FilterLimit
* works with raw queues and other low-cost paths.
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