From: Ian Rogers <irogers@google.com>
To: "Björn Töpel" <bjorn@kernel.org>,
"Magnus Karlsson" <magnus.karlsson@intel.com>,
"Maciej Fijalkowski" <maciej.fijalkowski@intel.com>,
"Jonathan Lemon" <jonathan.lemon@gmail.com>,
"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Martin KaFai Lau" <martin.lau@linux.dev>,
"Song Liu" <song@kernel.org>, "Yonghong Song" <yhs@fb.com>,
"John Fastabend" <john.fastabend@gmail.com>,
"KP Singh" <kpsingh@kernel.org>,
"Stanislav Fomichev" <sdf@google.com>,
"Hao Luo" <haoluo@google.com>, "Jiri Olsa" <jolsa@kernel.org>,
"Mykola Lysenko" <mykolal@fb.com>,
"Shuah Khan" <shuah@kernel.org>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Ian Rogers <irogers@google.com>
Subject: [PATCH v1] selftests/xsk: Avoid use-after-free on ctx
Date: Thu, 1 Sep 2022 13:26:45 -0700 [thread overview]
Message-ID: <20220901202645.1463552-1-irogers@google.com> (raw)
The put lowers the reference count to 0 and frees ctx, reading it
afterwards is invalid. Move the put after the uses and determine the
last use by the reference count being 1.
Fixes: 39e940d4abfa ("selftests/xsk: Destroy BPF resources only when ctx refcount drops to 0")
Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/testing/selftests/bpf/xsk.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/bpf/xsk.c b/tools/testing/selftests/bpf/xsk.c
index f2721a4ae7c5..0b3ff49c740d 100644
--- a/tools/testing/selftests/bpf/xsk.c
+++ b/tools/testing/selftests/bpf/xsk.c
@@ -1237,15 +1237,15 @@ void xsk_socket__delete(struct xsk_socket *xsk)
ctx = xsk->ctx;
umem = ctx->umem;
- xsk_put_ctx(ctx, true);
-
- if (!ctx->refcount) {
+ if (ctx->refcount == 1) {
xsk_delete_bpf_maps(xsk);
close(ctx->prog_fd);
if (ctx->has_bpf_link)
close(ctx->link_fd);
}
+ xsk_put_ctx(ctx, true);
+
err = xsk_get_mmap_offsets(xsk->fd, &off);
if (!err) {
if (xsk->rx) {
--
2.37.2.789.g6183377224-goog
next reply other threads:[~2022-09-01 20:27 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-01 20:26 Ian Rogers [this message]
2022-09-02 6:15 ` [PATCH v1] selftests/xsk: Avoid use-after-free on ctx Magnus Karlsson
2022-09-02 14:00 ` patchwork-bot+netdevbpf
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