Date: Wed, 19 Oct 2022 20:10:13 +0200 From: David Bouman <dbouman03@...il.com> To: oss-security@...ts.openwall.com Subject: Re: CVE-2022-2602 - Linux kernel io_uring UAF Hey, I found this vulnerability independently of ZDI, and reported it to the maintainers (this email address is stated in the patch). I can verify that this issue is exploitable on 5.10 as well, the stated patch does not prevent the issue. Regards, David On Tue, 18 Oct 2022, 19:28 Thadeu Lima de Souza Cascardo < cascardo@...onical.com> wrote: > A local privilege escalation vulnerabilty involving Unix socket Garbage > Collection and io_uring was reported and fixed as: > > 0091bfc81741b8d3aeb3b7ab8636f911b2de6e80 ("io_uring/af_unix: defer > registered files gc to io_uring release") > > The vulnerability is a use-after-free that happens when an io_uring request > is being processed on a registered file and the Unix GC runs and frees the > io_uring fd and all the registered fds. The order at which the Unix GC > processes the inflight fds may lead to registered fds be freed before the > io_uring is released and has the chance to unregister and wait for such > requests to finish. > > One way to trigger this race condition is to use userfaultfd and other > similar strategies that cause the request to be held waiting for the > attacker to trigger the free. > > This issue was reported as ZDI-CAN-17428 and has been assigned > CVE-2022-2602. > > It affects upstream stable 5.4.y, 5.15.y and later versions. 5.10.y may be > mitigated by the fact that commit 0f2122045b946241a9e549c2a76cea54fa58a7ff > ("io_uring: don't rely on weak ->files references") is present, but it is > safer to apply the fixes. > > A PoC will be posted in 7 days, on October 25th. > > Cascardo. >
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