CVE-2026-23168

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> flex_proportions: make fprop_new_period() hardirq safe<br /> <br /> Bernd has reported a lockdep splat from flexible proportions code that is<br /> essentially complaining about the following race:<br /> <br /> <br /> run_timer_softirq - we are in softirq context<br /> call_timer_fn<br /> writeout_period<br /> fprop_new_period<br /> write_seqcount_begin(&amp;p-&gt;sequence);<br /> <br /> <br /> ...<br /> blk_mq_end_request()<br /> blk_update_request()<br /> ext4_end_bio()<br /> folio_end_writeback()<br /> __wb_writeout_add()<br /> __fprop_add_percpu_max()<br /> if (unlikely(max_frac sequence);<br /> - sees odd sequence so loops indefinitely<br /> <br /> Note that a deadlock like this is only possible if the bdi has configured<br /> maximum fraction of writeout throughput which is very rare in general but<br /> frequent for example for FUSE bdis. To fix this problem we have to make<br /> sure write section of the sequence counter is irqsafe.