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 3710F224B17; Wed, 4 Dec 2024 23:35:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733355354; cv=none; b=WGAPQtMEeP814/09pQ5nHwXJF+3q1VhSonpl8EnwualDfg/cP91S4jFm8HY+0wSxPTfJMw2jFkktgfZc68t/VimxYUzmrozh+D3nLZ7pV5EX8uUa/W6AgC56SpS2npL9SDiVLsp30lZ4Qs/xios2rXg3YdX103JtO3RJrhKXdGU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733355354; c=relaxed/simple; bh=LrCwv/xA6yOQwsDPd5GsKlTBmspBObiOds2AdXGx3pM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nPZDlEM8hzELnbr0icVWhhZUN1k6Q0oLuSkYlAwIb2SWDtICeyEJ8qWLpEQsxjSrM47YiKCivVVmBoSf3bupGv5kf501mcQMP53Gt084be8aC+RHZStjkhGfmesynbJH0OnNgCw8mWANPt5hqXDr4ZdQXN/0ERIlXNXUBqrN72c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=U8C8aS5y; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="U8C8aS5y" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 47B4BC4CED6; Wed, 4 Dec 2024 23:35:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733355354; bh=LrCwv/xA6yOQwsDPd5GsKlTBmspBObiOds2AdXGx3pM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=U8C8aS5y91RzMfAZRCcjr+/RhnCVeWGz74ckCnlYac+hkQMiIICgKSA3LCGclgeij r47vp+p68LsuIl83nuXj5n8QfgUZkjPXSyCAWxeBZZFw5+fPAsqr+2YqUE0DIFsgic MxVeK+uxkLzlTqcwSSad+OEO6oIj4twSj2oCJVQmO+SEN3/5U/xYYP9sHL4mU1jdPM V/A7wso4OxdL2vMt/IIGHa8Us6yGIwoNgYB0nXqp3QoM1QecrqekbnRfvuH/6r/WIF Wbo6GPifS1H7pmreg3Wnxz+ZDc+TxuI9vbmybSCMeURg8Byg6VmYnqk0BaugFlYqYf EMEDRRm4W1d/A== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Jens Axboe , syzbot+cc36d44ec9f368e443d3@syzkaller.appspotmail.com, Sasha Levin , asml.silence@gmail.com, io-uring@vger.kernel.org Subject: [PATCH AUTOSEL 6.6 6/6] io_uring/tctx: work around xa_store() allocation error issue Date: Wed, 4 Dec 2024 17:24:15 -0500 Message-ID: <20241204222425.2250046-6-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241204222425.2250046-1-sashal@kernel.org> References: <20241204222425.2250046-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.6.63 Content-Transfer-Encoding: 8bit From: Jens Axboe [ Upstream commit 7eb75ce7527129d7f1fee6951566af409a37a1c4 ] syzbot triggered the following WARN_ON: WARNING: CPU: 0 PID: 16 at io_uring/tctx.c:51 __io_uring_free+0xfa/0x140 io_uring/tctx.c:51 which is the WARN_ON_ONCE(!xa_empty(&tctx->xa)); sanity check in __io_uring_free() when a io_uring_task is going through its final put. The syzbot test case includes injecting memory allocation failures, and it very much looks like xa_store() can fail one of its memory allocations and end up with ->head being non-NULL even though no entries exist in the xarray. Until this issue gets sorted out, work around it by attempting to iterate entries in our xarray, and WARN_ON_ONCE() if one is found. Reported-by: syzbot+cc36d44ec9f368e443d3@syzkaller.appspotmail.com Link: https://lore.kernel.org/io-uring/673c1643.050a0220.87769.0066.GAE@google.com/ Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- io_uring/tctx.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/io_uring/tctx.c b/io_uring/tctx.c index c043fe93a3f23..84f6a83857204 100644 --- a/io_uring/tctx.c +++ b/io_uring/tctx.c @@ -47,8 +47,19 @@ static struct io_wq *io_init_wq_offload(struct io_ring_ctx *ctx, void __io_uring_free(struct task_struct *tsk) { struct io_uring_task *tctx = tsk->io_uring; + struct io_tctx_node *node; + unsigned long index; - WARN_ON_ONCE(!xa_empty(&tctx->xa)); + /* + * Fault injection forcing allocation errors in the xa_store() path + * can lead to xa_empty() returning false, even though no actual + * node is stored in the xarray. Until that gets sorted out, attempt + * an iteration here and warn if any entries are found. + */ + xa_for_each(&tctx->xa, index, node) { + WARN_ON_ONCE(1); + break; + } WARN_ON_ONCE(tctx->io_wq); WARN_ON_ONCE(tctx->cached_refs); -- 2.43.0