Re: [PATCH v3 1/2] lib/idr: fix infinite loop in idr_get_next()

Andrew Morton
2026-03-12T20:55:19Z

On Thu, 12 Mar 2026 18:19:47 +0000 Josh Law <hlcj1234567@gmail.com> wrote:

> In idr_get_next(), if the returned id from idr_get_next_ul() is greater
> than INT_MAX, the function issues a warning and returns NULL without
> updating the *nextid pointer. This causes a soft lockup for any caller
> iterating over an IDR (e.g. via idr_for_each_entry) because they will
> receive NULL, fail to advance their index, and repeatedly query the same
> state forever.

This assumes that the idr_get_next() caller ignores the NULL return and
just keeps on looping. Isn't that a caller bug and if so, do we need
to defend against it here?