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Fri, 16 Oct 2026 10:47:18 -0700 (PDT) Received: from localhost ([153.61.198.254]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3ac94792925sm9835712a91.13.2026.10.16.10.47.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 16 Oct 2026 10:47:18 -0700 (PDT) Content-Type: text/plain; charset=UTF-8 Date: Fri, 16 Oct 2026 17:47:18 +0000 Message-Id: Cc: , "Quentin Monnet" , "Tianyi Chen" , "KP Singh" Subject: Re: [PATCH bpf-next] bpf: Don't echo user-supplied map info fields back to userspace From: "Alexei Starovoitov" To: "Daniel Borkmann" In-Reply-To: <20261016164153.656430-1-daniel@iogearbox.net> References: <20261016164153.656430-1-daniel@iogearbox.net> X-Mailer: mkdraft (claude review draft; edit before sending) Content-Transfer-Encoding: 8bit Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Fri, Oct 16, 2026 at 06:41 PM Daniel Borkmann wrote: > @@ -5450,7 +5451,11 @@ static int bpf_map_get_info_by_fd(struct file *file, > memset(&info, 0, sizeof(info)); > if (copy_from_user(&info, uinfo, info_len)) > return -EFAULT; > - > + hash = info.hash; > + hash_size = info.hash_size; > + memset(&info, 0, sizeof(info)); > + info.hash = hash; > + info.hash_size = hash_size; can we do memset(&info, 0, offsetof(struct bpf_map_info, hash)); here instead ? hash and hash_size are the last two fields and the padding after them is checked by bpf_check_uarg_tail_zero() above. Then no need for two extra variables and the 2nd full memset.