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(unknown [202.112.238.121]) by web2 (Coremail) with SMTP id yQQGZQAH4Jfb7y9qtBtQAg--.40734S2; Mon, 15 Jun 2026 20:28:24 +0800 (CST) From: Yiyang Chen To: bpf@vger.kernel.org Cc: Yiyang Chen , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , John Fastabend , Shuah Khan , linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH bpf v2 0/2] bpf: Fix packet pointer invalidation for skb dynptr writes Date: Mon, 15 Jun 2026 12:28:08 +0000 Message-Id: X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:yQQGZQAH4Jfb7y9qtBtQAg--.40734S2 X-Coremail-Antispam: 1UD129KBjvJXoW7uFW5Cr45ZF4rJFy5Kw4rKrg_yoW8Ww15pa yrGryYqrykZF13ArnxJF409rn8Ga18XF43Ga47try5Zwn8XrWYqFy2gr1UAFyrKr4fXw4S vFyaq3s5CFy5CrJanT9S1TB71UUUUjUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUmEb7Iv0xC_Cr1lb4IE77IF4wAFF20E14v26r4j6ryUM7CY07I2 0VC2zVCF04k26cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rw A2F7IY1VAKz4vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xII jxv20xvEc7CjxVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwV C2z280aVCY1x0267AKxVW0oVCq3wAaw2AFwI0_Jrv_JF1lnxkEFVAIw20F6cxK64vIFxWl e2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI 8IcVAFwI0_JrI_JrylYx0Ex4A2jsIE14v26r4j6F4UMcvjeVCFs4IE7xkEbVWUJVW8JwAC jcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lFIxGxcIEc7CjxVA2Y2ka0x kIwI1lc7CjxVAaw2AFwI0_Wrv_ZF1lc2xSY4AK67AK6ryUMxAIw28IcxkI7VAKI48JMxC2 0s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI 0_JrI_JrWlx4CE17CEb7AF67AKxVW8ZVWrXwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE 14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAIw20EY4v20x vaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AKxVW8 JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7xRXZ2VDUUUUU== X-CM-SenderInfo: xfkh05r1stqzpdlo2hxwvl0wxkxdhvlgxou0/ skb-backed dynptr writer kfuncs can mutate skb packet data. The verifier does not currently treat those kfuncs as packet-changing. A direct packet pointer checked before the call can stay usable after the write. bpf_dynptr_write() already clears packet pointers through the helper path. Teach kfunc argument checking to do the same for skb and skb-meta dynptr destinations. Keep source-only dynptr arguments unchanged. Validation: Without this series: linux-stable-v7.0.12 accepts the three stale packet pointer cases; linux-mainline-v7.1-rc7 accepts the three stale packet pointer cases; the source-only bpf_dynptr_copy() control loads on both kernels. With this series applied: patched bpf-next rejects the three stale packet pointer cases with "invalid mem access 'scalar'"; the source-only bpf_dynptr_copy() control still loads. Build and style checks: git diff --check: OK checkpatch.pl --strict --no-tree: OK make O=$BUILD kernel/bpf/verifier.o: OK make O=$BUILD -j$(nproc) bzImage: OK dynptr_fail.bpf.o build against patched vmlinux BTF: OK Signed-off-by: Yiyang Chen --- Changes in v2: - Resend as a properly threaded series. No code changes. Yiyang Chen (2): bpf: Fix packet pointer invalidation for skb dynptr writes selftests/bpf: Add skb dynptr writer packet invalidation tests include/linux/bpf_verifier.h | 1 + kernel/bpf/verifier.c | 62 ++++++++++++- .../testing/selftests/bpf/progs/dynptr_fail.c | 89 +++++++++++++++++++ 3 files changed, 151 insertions(+), 1 deletion(-) base-commit: e4287bf34f97a88c7d9322f5bde828724c073a6b -- 2.34.1