linux-kernel - [PATCH v1 1/3] Revert "cgroup: enable cgroup_get_from

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Date:   Mon, 10 Oct 2022 23:58:43 +0000
From:   Yosry Ahmed <yosryahmed@...gle.com>
To:     Tejun Heo <tj@...nel.org>, Zefan Li <lizefan.x@...edance.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Yonghong Song <yhs@...com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>
Cc:     cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
        bpf@...r.kernel.org, Yosry Ahmed <yosryahmed@...gle.com>,
        "Christian A . Ehrhardt" <lk@...e.de>
Subject: [PATCH v1 1/3] Revert "cgroup: enable cgroup_get_from_file() on cgroup1"

This reverts commit f3a2aebdd6fb90e444d595e46de64e822af419da.

Some callers of this function depended on the fact that it only supports
cgroup v2. Revert it now, and introduce a new function in a later patch
that supports both cgroup v1 and v2, for callers that need to support
both.

Reported-by: Christian A. Ehrhardt <lk@...e.de>
Signed-off-by: Yosry Ahmed <yosryahmed@...gle.com>
---
 kernel/cgroup/cgroup.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 764bdd5fd8d1..72e97422e9d9 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -6218,6 +6218,11 @@ static struct cgroup *cgroup_get_from_file(struct file *f)
 		return ERR_CAST(css);
 
 	cgrp = css->cgroup;
+	if (!cgroup_on_dfl(cgrp)) {
+		cgroup_put(cgrp);
+		return ERR_PTR(-EBADF);
+	}
+
 	return cgrp;
 }
 
-- 
2.38.0.rc1.362.ged0d419d3c-goog