From: Dave Marchevsky <davemarchevsky@fb.com>
To: <bpf@vger.kernel.org>
Cc: <kernel-team@fb.com>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
Dave Marchevsky <davemarchevsky@fb.com>
Subject: [PATCH bpf-next v2 0/3] bpf: refine retval for bpf_get_task_stack helper
Date: Fri, 16 Apr 2021 13:47:01 -0700 [thread overview]
Message-ID: <20210416204704.2816874-1-davemarchevsky@fb.com> (raw)
Similarly to the bpf_get_stack helper, bpf_get_task_stack's return value
can be more tightly bound by the verifier - it's the number of bytes
written to a user-supplied buffer, or a negative error value. Currently
the verifier believes bpf_task_get_stack's retval bounds to be unknown,
requiring extraneous bounds checking to remedy.
Adding it to do_refine_retval_range fixes the issue, as evidenced by
new selftests which fail to load if retval bounds are not refined.
v2: Addressed comment nit in patch 3
Dave Marchevsky (3):
bpf: refine retval for bpf_get_task_stack helper
bpf/selftests: add bpf_get_task_stack retval bounds verifier test
bpf/selftests: add bpf_get_task_stack retval bounds test_prog
kernel/bpf/verifier.c | 1 +
.../selftests/bpf/prog_tests/bpf_iter.c | 1 +
.../selftests/bpf/progs/bpf_iter_task_stack.c | 27 ++++++++++++
.../selftests/bpf/verifier/bpf_get_stack.c | 43 +++++++++++++++++++
4 files changed, 72 insertions(+)
--
2.30.2
next reply other threads:[~2021-04-16 20:47 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-16 20:47 Dave Marchevsky [this message]
2021-04-16 20:47 ` [PATCH bpf-next v2 1/3] bpf: refine retval for bpf_get_task_stack helper Dave Marchevsky
2021-04-16 20:47 ` [PATCH bpf-next v2 2/3] bpf/selftests: add bpf_get_task_stack retval bounds verifier test Dave Marchevsky
2021-04-16 20:47 ` [PATCH bpf-next v2 3/3] bpf/selftests: add bpf_get_task_stack retval bounds test_prog Dave Marchevsky
2021-04-20 2:20 ` [PATCH bpf-next v2 0/3] bpf: refine retval for bpf_get_task_stack helper Alexei Starovoitov
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