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([2001:41d0:303:db6b::]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4923fd1fa34sm371339255e9.5.2026.06.22.16.01.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Jun 2026 16:01:24 -0700 (PDT) From: Tristan Madani To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: Eduard Zingerman , Xu Kuohai , Jiri Olsa , John Fastabend , Martin KaFai Lau , bpf@vger.kernel.org, stable@vger.kernel.org, tristan@talencesecurity.com Subject: [PATCH bpf v3 0/2] Fix stale register bounds on LSM retval context load Date: Mon, 22 Jun 2026 23:01:21 +0000 Message-ID: <20260622230123.3695446-1-tristmd@gmail.com> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Tristan Madani check_mem_access() calls __mark_reg_s32_range() to narrow a register to the LSM hook retval range, but the intersection preserves stale bounds from prior instructions. Add mark_reg_unknown() before narrowing (same pattern as the else branch) and a selftest that catches the mismatch. Changes in v3: - Add selftest demonstrating the issue (Eduard Zingerman) - No code change in patch 1 from v2 Tristan Madani (2): bpf: Reset register bounds before narrowing retval range in check_mem_access() selftests/bpf: Add test for stale bounds on LSM retval context load kernel/bpf/verifier.c | 1 + tools/testing/selftests/bpf/progs/verifier_lsm.c | 15 +++++++++++++++ 2 files changed, 16 insertions(+) -- 2.47.3