linux-kernel - [PATCH 4.14 v3 0/4] BPF fixes for CVE-2021-3444 and CVE-2021-3600

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Date:   Fri, 24 Feb 2023 03:40:15 +0000
From:   Edward Liaw <edliaw@...gle.com>
To:     stable@...r.kernel.org, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S. Miller" <davem@...emloft.net>
Cc:     bpf@...r.kernel.org, kernel-team@...roid.com,
        Edward Liaw <edliaw@...gle.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 4.14 v3 0/4] BPF fixes for CVE-2021-3444 and CVE-2021-3600

Thadeu Lima de Souza Cascardo originally sent this patch but it failed to
merge because of a compilation error:

https://lore.kernel.org/bpf/20210830183211.339054-1-cascardo@canonical.com/T/

v3:
Added upstream commit hash from 4.19.y and added detail to changelog.

v2:
Removed redefinition of tmp to fix compilation with CONFIG_BPF_JIT_ALWAYS_ON
enabled.

-Edward

==

The upstream changes necessary to fix these CVEs rely on the presence of JMP32,
which is not a small backport and brings its own potential set of necessary
follow-ups.

Daniel Borkmann, John Fastabend and Alexei Starovoitov came up with a fix
involving the use of the AX register.

This has been tested against the test_verifier in 4.14.y tree and some tests
specific to the two referred CVEs. The test_bpf module was also tested.

Daniel Borkmann (4):
  bpf: Do not use ax register in interpreter on div/mod
  bpf: fix subprog verifier bypass by div/mod by 0 exception
  bpf: Fix 32 bit src register truncation on div/mod
  bpf: Fix truncation handling for mod32 dst reg wrt zero

 include/linux/filter.h | 24 ++++++++++++++++++++++++
 kernel/bpf/core.c      | 39 ++++++++++++++-------------------------
 kernel/bpf/verifier.c  | 39 +++++++++++++++++++++++++++++++--------
 net/core/filter.c      |  9 ++++++++-
 4 files changed, 77 insertions(+), 34 deletions(-)

base-commit: a8ad60f2af5884921167e8cede5784c7849884b2
-- 
2.39.2.637.g21b0678d19-goog