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 441AA226EDC; Wed, 4 Dec 2024 23:36:08 +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=1733355369; cv=none; b=TsPPeir5rmF5fv/vhA9QglTn6p6njiJWV7n3ySvPGZlWRYzfxyeq65ekP7lC9aaBJH81XDsgoDqC5sKxsuRhjy9fzaMVJKgY5XI2RaO5VRR1IMrox1/f0tJKh8CPNrzh1MNN0cJtFJNq4zuAlII2xs44TCkJYRdNlL+K5HNBMa4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733355369; c=relaxed/simple; bh=su6DGtx91bYNMGzrJMR47XvYAvuxo7/HbpJbzxf8zqs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DdnsFPurFJK1YHrMya7hprGteQOYI6evd/f5jpdEAImu8r7VPGKxDdqtUvDyRQ6yOFvptxxOkGiFMNk4H1VL6hrzg63FhyInmfkZfG17XoLr8G3oc0S1RZMLz7fwIo8SOqf4eTpVC8O/yo7sddM7VHKJTomKFl/D4CvxL4m86bI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=oRukhFpe; 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="oRukhFpe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0D9E0C4CED2; Wed, 4 Dec 2024 23:36:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733355368; bh=su6DGtx91bYNMGzrJMR47XvYAvuxo7/HbpJbzxf8zqs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oRukhFpev+GX8McRA8vuwcpyJDiFLPe7WqwGSXIn+HinSv9DUvLrC8LJ4LN73egZg 1/rfQJ0DJXPjHEAVN01TV7An1mUJZkHEfjZkqOCtwYhhBGuJKMg1QH84UsRsooV272 tk4hkVJ729I1lscsUnKGtk1Lwxn9K07wFKGKtAgeNu202sF0Dl0ZwTuj/RPWODnZFx Obc5cV1fOVkJ9UTB8cFDVMXCNL/f9oMi8tiW0SyuVcy7cbwMBJwTYz8s29Y+V9Y4i2 J2kTopomlqb3WGBKOhrpU5Jrh8mWodFW5DuPDLC9yU2PuxiF0I/JxalvTYUlxnGfOF 4GITASEGPJ/IQ== 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 6.1 4/4] io_uring/tctx: work around xa_store() allocation error issue Date: Wed, 4 Dec 2024 17:24:36 -0500 Message-ID: <20241204222444.2250332-4-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241204222444.2250332-1-sashal@kernel.org> References: <20241204222444.2250332-1-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 6.1.119 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 4324b1cf1f6af..51b05fda8e455 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