From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B24322EB15; Fri, 24 Nov 2023 19:21:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Dhc49M/C" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3FC57C433C8; Fri, 24 Nov 2023 19:21:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1700853718; bh=bNm+qmKKAT1UT2yBM5au/HrDXyHACJ6XlMhXtBdmAlY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Dhc49M/CfJa1sEmiccaK+BQg+4lZSqxWhdejkMVDfdXafKJXhjsKQv4uDlIzsKUu0 kNG+IHazl65iTi74C2yDcWjjVNg0y1nxEtDm9Rlu9SwNmddqlIkvTW2lrU7YLWcmSk mpR0F13wLIdkVu20Yk0x1Fa658VkHx9tFbdbtceU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Gabriel Krisman Bertazi , Jens Axboe , He Gao Subject: [PATCH 5.15 293/297] io_uring/fdinfo: lock SQ thread while retrieving thread cpu/pid Date: Fri, 24 Nov 2023 17:55:35 +0000 Message-ID: <20231124172010.366727360@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231124172000.087816911@linuxfoundation.org> References: <20231124172000.087816911@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jens Axboe commit 7644b1a1c9a7ae8ab99175989bfc8676055edb46 upstream. We could race with SQ thread exit, and if we do, we'll hit a NULL pointer dereference when the thread is cleared. Grab the SQPOLL data lock before attempting to get the task cpu and pid for fdinfo, this ensures we have a stable view of it. Cc: stable@vger.kernel.org Link: https://bugzilla.kernel.org/show_bug.cgi?id=218032 Reviewed-by: Gabriel Krisman Bertazi Signed-off-by: Jens Axboe Signed-off-by: He Gao Signed-off-by: Greg Kroah-Hartman --- io_uring/io_uring.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -10411,7 +10411,7 @@ static int io_uring_show_cred(struct seq static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m) { - struct io_sq_data *sq = NULL; + int sq_pid = -1, sq_cpu = -1; bool has_lock; int i; @@ -10424,13 +10424,19 @@ static void __io_uring_show_fdinfo(struc has_lock = mutex_trylock(&ctx->uring_lock); if (has_lock && (ctx->flags & IORING_SETUP_SQPOLL)) { - sq = ctx->sq_data; - if (!sq->thread) - sq = NULL; + struct io_sq_data *sq = ctx->sq_data; + + if (mutex_trylock(&sq->lock)) { + if (sq->thread) { + sq_pid = task_pid_nr(sq->thread); + sq_cpu = task_cpu(sq->thread); + } + mutex_unlock(&sq->lock); + } } - seq_printf(m, "SqThread:\t%d\n", sq ? task_pid_nr(sq->thread) : -1); - seq_printf(m, "SqThreadCpu:\t%d\n", sq ? task_cpu(sq->thread) : -1); + seq_printf(m, "SqThread:\t%d\n", sq_pid); + seq_printf(m, "SqThreadCpu:\t%d\n", sq_cpu); seq_printf(m, "UserFiles:\t%u\n", ctx->nr_user_files); for (i = 0; has_lock && i < ctx->nr_user_files; i++) { struct file *f = io_file_from_index(ctx, i);