From: Yonghong Song <yhs@fb.com>
To: <bpf@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>, <kernel-team@fb.com>
Subject: [PATCH bpf 0/2] bpf: fix a verifier issue when assigning 32bit reg states to 64bit ones
Date: Thu, 28 May 2020 09:50:43 -0700 [thread overview]
Message-ID: <20200528165043.1568623-1-yhs@fb.com> (raw)
Commit 3f50f132d840 ("bpf: Verifier, do explicit ALU32 bounds tracking")
added 32bit register states to verifier for explicit ALU32 bounds
tracking. When assigning 32bit register states to 64bit register states,
if 32bit register is a constant value of 0, the 64bit register smax_val
will get U32_MAX(0xffffFFFF). Such an inprecise information may impact
downward verification. Patch #1 has detailed explanation of the program
and how to fix it. Patch #2 provides a verifier test to cover the change.
Yonghong Song (2):
bpf: fix a verifier issue when assigning 32bit reg states to 64bit
tools/bpf: add a verifier test for assigning 32bit reg states to 64bit
kernel/bpf/verifier.c | 3 +++
tools/testing/selftests/bpf/verifier/bounds.c | 22 +++++++++++++++++++
2 files changed, 25 insertions(+)
--
2.24.1
next reply other threads:[~2020-05-28 16:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-28 16:50 Yonghong Song [this message]
2020-05-28 16:50 ` [PATCH bpf 1/2] bpf: fix a verifier issue when assigning 32bit reg states to 64bit ones Yonghong Song
2020-05-28 20:36 ` Alexei Starovoitov
2020-05-28 21:22 ` Yonghong Song
2020-05-28 21:30 ` John Fastabend
2020-05-28 21:58 ` Yonghong Song
2020-05-28 16:50 ` [PATCH bpf 2/2] tools/bpf: add a verifier test for " Yonghong Song
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