From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793214201; b=VH2B3aBHoXyIi6eH2qq9XUoX8nZ0UOum/2MsIleT3ySLAo29sBR8U+U5PiV4LhGv4whX fJQL5h1YcB3C5nsTsfBQtiEU1ZnhogsG6AcnNTRoCHuVI2pgbqev9YtfBKzDJPIx5TwLR jxGe6c+HOmOuJrCOv/gt/shN29NEUUR1qEYW8PWGJNkhJoirVrjxus8A2Sqv98RfLPkZ3 HNj0+8wEj/umglte9Gie+8pA6QnFs4vGC80sJ2SrO9xpYb04/U+DsVpDEaoXLFvQFoUoA dbaKA7qml04eLR6HhlKc8jd1lNZTRaF4/Mkx0bjRXW6tdOvfew/CQ/Znz+kPwwadGHg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793214201; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=3NKg7E602YNWIS7gNqk7cF6kW5vAxqI0J5F8mbPed8g=; b=upMWD9Wlh+AMheuXsdpz9krbItGq/wCLhJkxK+gblDZ/xNHt9waB2dAzDIyuHN5/SVcB 4Qzg5gLahhKaxVa6LjUn99DFtivljowp93PMpX9dczfAscK7qL+FtoHfO7rtzXE5djn88 /Zk20elscJ8EXzNW0EHaBhzWhqnMOXvVETktrpbdajPORhd4lth0Ti7n/fEUhMoL+cq+O dZrTwOm+qwzW5dn473z5iPoJj0HbL0QquasNy8p07XuqMOg7UKedTXMK6mondGUHh3i9U Yc8qo0Zq/kn6hkE6dGsc0AH6skznKRT3NzVFJGuU9Zt6qW+XTbtJ36pkMdkzGw1RUHA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Lu8p9hwG; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 02570606BF93 for ; Wed, 28 Oct 2026 19:03:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Lu8p9hwG Received: by smtp.kernel.org (Postfix) with ESMTPSA id 382F81F013C2; Wed, 28 Oct 2026 19:03:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793214200; bh=3NKg7E602YNWIS7gNqk7cF6kW5vAxqI0J5F8mbPed8g=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Lu8p9hwGJJL01gG4czJzzRG1nXRJvhkxsXZFiLRC7323aPKJFt0oOWpJ2701BF5Ds 3bPB3w7Ze03qspvVt/Zp2tsnEkFTVRkTP0xT1fj9Xr1pw82UgVkiEdOcM8y5BtFtFd bpww4wEcqAJJlMuOqPeEgg6uK0ZSKmN1EKTMGvmcNSLSbVCOJ+gD4qZtv6ZSq/ROJH DMXbysFdu+TLCQOjrvaqX7RFSBIKWFLfI5dEikfSrIKais1FO3p2pev5bESSp1vXEy aDHhl3eDv+GCsajmNB5o5nZ9oNktJvibaeIngcJo9zs6wvVouWCXukCZ3FD4K0XI01 t6IPc4NvBLZRg== From: Sasha Levin To: stable@vger.kernel.org Cc: Christian Brauner , Oleg Nesterov , Jens Axboe , Sasha Levin Subject: [PATCH 7.2.y] exec: cancel io_uring requests before de_thread() Date: Wed, 28 Oct 2026 15:03:19 -0400 Message-ID: <20261028190311.2073244-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026102818-halt-spruce-26fc@gregkh> References: <2026102818-halt-spruce-26fc@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Christian Brauner [ Upstream commit b42c85c20d84ff3e4f0f027d6596c3b3b4a20657 ] begin_new_exec() cancels the exec'ing thread's io_uring requests after de_thread() made it the only thread in the thread-group. Now io_uring_task_cancel() runs task work after. If it runs a create_worker_cb() item then a io-wq queued on the thread before the exec creates a new io-wq worker thread. Said thread joins the thread-group which de_thread() just took down. The io-iwq sticks around until it notices that its workqueue is dying. But code after de_thread() relies on being single-threaded. Move io_uring_task_cancel() before de_thread() but behind the point of no return. Any worker created during task work run from io_uring_task_cancel() is just a sibling thread that de_thread() will take down and reap. Once io_uring_task_cancel() returned the thread has neither a task context nor a workqueue left so nothing can add a thread behind de_thread()'s back anymore. Suggested-by: Oleg Nesterov Link: https://lore.kernel.org/r/aq0_lvHDViIpX_Mu@redhat.com Fixes: 3bfe6106693b ("io-wq: fork worker threads from original task") Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260921-work-coredump-fixes-v3-12-8e4adb1619e6@kernel.org Acked-by: Oleg Nesterov Reviewed-by: Jens Axboe Signed-off-by: Christian Brauner (Amutable) Signed-off-by: Sasha Levin --- fs/exec.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index a598d48b5ffcc..bd3e3aac90efd 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1145,6 +1145,13 @@ int begin_new_exec(struct linux_binprm * bprm) */ bprm->point_of_no_return = true; + /* + * Cancel any io_uring activity across execve. This runs task work + * that may still create an io-wq worker, so do it while de_thread() + * can still zap it. + */ + io_uring_task_cancel(); + /* Make this the only thread in the thread group */ retval = de_thread(me); if (retval) @@ -1161,10 +1168,6 @@ int begin_new_exec(struct linux_binprm * bprm) /* see the comment in check_unsafe_exec() */ current->fs->in_exec = 0; - /* - * Cancel any io_uring activity across execve - */ - io_uring_task_cancel(); /* Ensure the files table is not shared. */ retval = unshare_files(); -- 2.53.0