From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.250 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794411110; b=Z0tsBUt6LA6Ieu3wglzfkvQOKN6nD8OSa+mVDECKW0rh2anwf4FH3vOdfvWJtEkLakzo xIWWcayDpYK/HLc4HBhXOo7DmSxPE8gzD2EDZPROqDlqPQh7V5gEzMbVFkZ9cSNlFvYhF 9bTaTgzUiuC9J+x4UDYPMunA2kxjKScMYsC6owyJr8mfi2bDegiD7HqKh1UnNjwM0oASt v1ORvJX1a0Hx30lQy8Rj6epQLKHzhtExm8Dmd5uBVQizIa15J2L0oj5nE9fjW+J7pkrzX Xmb5GaIZ4YXkdaFOvHrwK7rtjucstl5k5dAaKBz3ZtbMMPx1GLphyO8QbndcFZ4g6tA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794411110; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:Content-Language:From:In-Reply-To: Content-Type:Content-Transfer-Encoding; bh=yEIA6Zmz02BTCzQZDjg7NRu0QFN0RHxgpEwj9oihF+4=; b=UgSNDx7CZtWxJh6G8/NfsIh2FCgegFjcwkngBTMSJXOIIDRACaAa1UD72jATWIGiaD45 Ry4Jw76HOAf4aLM6QtLoOpxljLlVsGSt8GurAJf5OBsd9s5po7x6Hk3ETMpUOi0BtfXAD 5SDKxMovidYij7HCyJGjF05MeCDn/48MhpaWIJ9bhpV6Zf9QuUP0sLLFAyanfrS/FcHlg OnH+c400E1A0oJ/iYd6bEpsSTU1TJKbfoEfq7n9TMRxSON5SV3V4RxxqXXoen0GJ01CB3 ZJKhhb5ZBH+GFwrD9tGbhc4fYY9SKECGDhJGm9+i6fFqUXhj6MExKLLp7GAKGCMJETQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=dBZM5A4l; arc=none smtp.remote-ip=91.218.175.250 Received: from mta0.migadu.com (out-250.mta0.migadu.com [91.218.175.250]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A9103606A321 for ; Wed, 11 Nov 2026 15:31:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org A9103606A321 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=dBZM5A4l X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=NjcZ2vs086wrkeO3l/vjfd5QbHjdbw8ASBFYAH9BBjE=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1794411107; v=1; x=1795015907; b=dBZM5A4lIIKKb7ticjEP2eL/HioI0Hp1LgmI4yAus5DfyRQ2BAewrMRWVlfwISZ0fmb5ZrnN vMNRzU8i3WB6GJV3ama9V+u83WeUZTapB9u0P6+zbS9LqJHyYmZlmd2Sk9adM6zZuot1RHI561Y H4C/KL00Vc2UzkOB9/croRyg= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 59aee4a50207fa8f; Wed, 11 Nov 2026 15:31:47 +0000 X-Mizu-Trace-ID: 59aee4a50207fa8f X-Migadu-Flow: FLOW_OUT Message-ID: <28d1e284-501f-47f8-b155-bbc2255f7a06@linux.dev> Date: Wed, 11 Nov 2026 23:31:35 +0800 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH bpf-next 1/9] bpf: Add log support for tracing link_create To: bot+bpf-ci@kernel.org, bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, andrii@kernel.org, eddyz87@gmail.com, memxor@gmail.com, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, emil@etsalapatis.com, ihor.solodrai@linux.dev, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, kpsingh@kernel.org, matt@bobrowski.net, shuah@kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, netdev@vger.kernel.org, martin.lau@kernel.org, mason@kernel.org References: <20261109140816.5196-2-leon.hwang@linux.dev> <5ed2ec09ce8a3ce5477a658b68c6315499ef67793014be27de18ee57ec968e12@mail.kernel.org> Content-Language: en-US From: Leon Hwang In-Reply-To: <5ed2ec09ce8a3ce5477a658b68c6315499ef67793014be27de18ee57ec968e12@mail.kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2026/11/9 22:47, bot+bpf-ci@kernel.org wrote: >> bpf: Add log support for tracing link_create > > TL;DR: Logging is incomplete: the freplace max_ctx_offset check in > bpf_tracing_prog_attach() still returns -EINVAL with an empty log, and the > saved_dst type mismatch may too. No functional regression. > >> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c >> --- a/kernel/bpf/syscall.c >> +++ b/kernel/bpf/syscall.c > > [ ... ] > >> @@ -3843,6 +3849,7 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, >> */ >> if (prog->type == BPF_PROG_TYPE_EXT && >> prog->aux->kprobe_write_ctx != tgt_prog->aux->kprobe_write_ctx) { >> + bpf_log(log, "Invalid kprobe_write_ctx.\n"); >> err = -EINVAL; >> goto out_unlock; >> } > > The check right after this one still returns -EINVAL without writing > anything to the log: > > if (prog->type == BPF_PROG_TYPE_EXT && > (tgt_prog->type == BPF_PROG_TYPE_RAW_TRACEPOINT || > tgt_prog->type == BPF_PROG_TYPE_TRACEPOINT || > tgt_prog->type == BPF_PROG_TYPE_SYSCALL) && > prog->aux->max_ctx_offset > tgt_prog->aux->max_ctx_offset) { > err = -EINVAL; > goto out_unlock; > } > > An freplace program whose max_ctx_offset is larger than that of a > RAW_TRACEPOINT, TRACEPOINT or SYSCALL target will get -EINVAL from > link_create with an empty log and log_true_size of 0. That is the same > kind of invalid freplace target as the kprobe_write_ctx mismatch above, > which now logs. This isn't a functional regression, but was this check > missed? > > Would something like this cover it? > > bpf_log(log, "Extension accesses more ctx than its target.\n"); Will add such log in the next revision. > > Also, bpf_check_attach_target() still returns a bare -EINVAL for the > saved_dst_prog_type / saved_dst_attach_type mismatch, which is the > "freplace attachment to a new target" case the commit message mentions. > That code is in verifier.c, so it is outside this patch, but is it intended > to be left without a message? It was intentional to avoid touching bpf_check_attach_target() code. Thanks, Leon