Re: [PATCH v2] lib/idr: fix infinite loop in idr_get_next()

[Josh Law]

12 Mar 2026 17:26:44 Matthew Wilcox <willy@xxxxxxxxxxxxx>:

> On Thu, Mar 12, 2026 at 05:12:38PM +0000, Josh Law wrote:
>> From: Josh Law <objecting@xxxxxxxxxxxxx>
>>
>> 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.
>>
>> Fix this by setting *nextid to INT_MAX when the bounds check fails,
>> ensuring the caller's iteration will terminate.
>
> Can you add a test-case for this?  And the IDA patch you also sent?

Lmao you and your test cases, absolutely ill add some test cases