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From: "Cen Zhang (Microsoft)" <blbllhy@gmail.com>
To: include@grrlz.net
Cc: AutonomousCodeSecurity@microsoft.com, avagin@gmail.com,
	blbllhy@gmail.com, brauner@kernel.org, jack@suse.cz,
	kys@microsoft.com, linux-kernel@vger.kernel.org,
	mjguzik@gmail.com, oleg@redhat.com, ptikhomirov@virtuozzo.com,
	tgopinath@linux.microsoft.com
Subject: Re: [PATCH] pid: fix cad_pid use-after-free race in proc_do_cad_pid()
Date: Fri, 17 Jul 2026 21:33:25 -0400	[thread overview]
Message-ID: <20260718013325.5651-1-blbllhy@gmail.com> (raw)
In-Reply-To: <D5781615-F6BD-4510-AAEB-8972B5C5828E@grrlz.net>

Thanks both for the review.

One impact clarification: this is not init-namespace-root-only. The sysctl
is mode 0600, but access is checked against the owning user namespace, so
an unprivileged user can reach it via userns + pidns + a proc mount.

The demonstrated impact is a KASAN UAF. On non-debug builds the
proc_do_cad_pid() read path likely only returns a stale pid value unless
the freed pid object is reused in a very tight window.

I'll send a v2 series as suggested: patch 1 deinlines kill_cad_pid()
without functional changes, and patch 2 contains the updated fix.


      reply	other threads:[~2026-07-18  1:33 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-17 21:01 [PATCH] pid: fix cad_pid use-after-free race in proc_do_cad_pid() Cen Zhang (Microsoft)
2026-07-17 21:35 ` Mateusz Guzik
2026-07-17 23:14   ` Bradley Morgan
2026-07-18  1:33     ` Cen Zhang (Microsoft) [this message]

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