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 1/3] bpf: refine retval for bpf_get_task_stack helper
Date: Thu, 15 Apr 2021 19:55:35 -0700 [thread overview]
Message-ID: <20210416025537.2352753-2-davemarchevsky@fb.com> (raw)
In-Reply-To: <20210416025537.2352753-1-davemarchevsky@fb.com>
Verifier can constrain the min/max bounds of bpf_get_task_stack's return
value more tightly than the default tnum_unknown. Like bpf_get_stack,
return value is num bytes written into a caller-supplied buf, or error,
so do_refine_retval_range will work.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
---
kernel/bpf/verifier.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 852541a435ef..348e97f77003 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5767,6 +5767,7 @@ static void do_refine_retval_range(struct bpf_reg_state *regs, int ret_type,
if (ret_type != RET_INTEGER ||
(func_id != BPF_FUNC_get_stack &&
+ func_id != BPF_FUNC_get_task_stack &&
func_id != BPF_FUNC_probe_read_str &&
func_id != BPF_FUNC_probe_read_kernel_str &&
func_id != BPF_FUNC_probe_read_user_str))
--
2.30.2
next prev parent reply other threads:[~2021-04-16 2:56 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-16 2:55 [PATCH bpf-next 0/3] bpf: refine retval for bpf_get_task_stack helper Dave Marchevsky
2021-04-16 2:55 ` Dave Marchevsky [this message]
2021-04-16 16:53 ` [PATCH bpf-next 1/3] " Song Liu
2021-04-16 2:55 ` [PATCH bpf-next 2/3] bpf/selftests: add bpf_get_task_stack retval bounds verifier test Dave Marchevsky
2021-04-16 17:09 ` Song Liu
2021-04-16 2:55 ` [PATCH bpf-next 3/3] bpf/selftests: add bpf_get_task_stack retval bounds test_prog Dave Marchevsky
2021-04-16 17:06 ` Song Liu
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