From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 871FED711D5 for ; Fri, 19 Dec 2025 02:49:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C2F9B6B0088; Thu, 18 Dec 2025 21:49:44 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id BB3326B0089; Thu, 18 Dec 2025 21:49:44 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ABED06B008A; Thu, 18 Dec 2025 21:49:44 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 9449B6B0088 for ; Thu, 18 Dec 2025 21:49:44 -0500 (EST) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 3A1ADB9275 for ; Fri, 19 Dec 2025 02:49:44 +0000 (UTC) X-FDA: 84234690288.06.B48B301 Received: from out-185.mta0.migadu.com (out-185.mta0.migadu.com [91.218.175.185]) by imf10.hostedemail.com (Postfix) with ESMTP id 78EA1C000D for ; Fri, 19 Dec 2025 02:49:42 +0000 (UTC) Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=pI4nKNEv; spf=pass (imf10.hostedemail.com: domain of roman.gushchin@linux.dev designates 91.218.175.185 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1766112582; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=abd/44gPrDqvBL/2LyNnB1pB9d9gpdKplEObPG4utUA=; b=nri7jtWYm0Q/j2sHjgqcltpffm3gS9VuRWgrE1K/Wcc7QEKXnCBhD8g/0b1gKv5PQBh60K 7Qm+qlL7Wc8CI2u57pHfm5x1Y7+Dsrgc+SBKvhU2y6tuFi5LD9HPYKiMg/rJfuFdgzt2Dy lZtneuehvmPmbYBCJBxayojrt0FLgZs= ARC-Authentication-Results: i=1; imf10.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=pI4nKNEv; spf=pass (imf10.hostedemail.com: domain of roman.gushchin@linux.dev designates 91.218.175.185 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1766112582; a=rsa-sha256; cv=none; b=vzkuhl3efCSX0toXgxCTlorOYyg9MsMhwXy/+3UQUuEicLH/tQh85vaUp3C4rbyBP67DnZ aeFrkhlgkL3Wt+ZzXSoDRTl/KE+N2oS1AVXQN4FZtcKk86Z9ke8jKSHNlECuclBGxy51nc uXK5sljvew4GSCgg6uDE7lHQme06Gkg= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1766112576; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=abd/44gPrDqvBL/2LyNnB1pB9d9gpdKplEObPG4utUA=; b=pI4nKNEv57QpGkjms+FO+OVqvN/dvP3YiYsx0xarnEsiCnH4BErdFjMIC9Pe/5Z8eWZ+zv hmJofNw0nk7tikxTe/wsF8R16TfIFQmAvU/5WGTCVz8J0VCQiq5uL7Di6bdR/twt3OIc+a hFzrgZV0SJJtPpec9hJMioiFImoD1Go= From: Roman Gushchin To: bot+bpf-ci@kernel.org Cc: bpf@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, inwardvessel@gmail.com, ast@kernel.org, daniel@iogearbox.net, shakeel.butt@linux.dev, mhocko@kernel.org, hannes@cmpxchg.org, mhocko@suse.com, andrii@kernel.org, martin.lau@kernel.org, eddyz87@gmail.com, yonghong.song@linux.dev, clm@meta.com, ihor.solodrai@linux.dev Subject: Re: [PATCH bpf-next v1 4/6] mm: introduce BPF kfuncs to access memcg statistics and events In-Reply-To: (bot's message of "Fri, 19 Dec 2025 02:15:11 +0000 (UTC)") References: <20251219015750.23732-5-roman.gushchin@linux.dev> Date: Thu, 18 Dec 2025 18:49:29 -0800 Message-ID: <87bjjvb2yu.fsf@linux.dev> MIME-Version: 1.0 Content-Type: text/plain X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam02 X-Stat-Signature: s8wjkjp5shkju3dt5qju7jzhe1eqnxp9 X-Rspam-User: X-Rspamd-Queue-Id: 78EA1C000D X-HE-Tag: 1766112582-273445 X-HE-Meta: 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 2WGjki6v tFfXSLLdgD5EugZLSzRGxw65oA/wTj0f4mnilhlrvs1dBSbvwgH3kGv5xu/KEnOrkIR9UXCZm0U6esfSXgcfqk/I8zD7xwXfGIlAT0CTiK/ANNzop4Od/m735wVDoVDam8B7qTMRaSZTKpHrcYYfp52T/i4WWmWqYwyaBJX9jAXvgUX4si99lFVpvCkJ3jtmYcVkwWHi3A7vMDrNZMz01anf4g6N0MNZqS3PWY2HzApkYAujAHwLr5dDK4NY8HhShFX1Lagf6NnaKf0I= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: bot+bpf-ci@kernel.org writes: >> diff --git a/mm/bpf_memcontrol.c b/mm/bpf_memcontrol.c >> index 6d0d73bf0dd1..4d9d7d909f6c 100644 >> --- a/mm/bpf_memcontrol.c >> +++ b/mm/bpf_memcontrol.c > > [ ... ] > >> +/** >> + * bpf_mem_cgroup_vm_events - Read memory cgroup's vm event counter >> + * @memcg: memory cgroup >> + * @event: event id >> + * >> + * Allows to read memory cgroup event counters. >> + */ >> +__bpf_kfunc unsigned long bpf_mem_cgroup_vm_events(struct mem_cgroup *memcg, >> + enum vm_event_item event) >> +{ >> + return memcg_events(memcg, event); >> +} > > Should bpf_mem_cgroup_vm_events() validate the event parameter before > passing it to memcg_events()? The call chain is: > > bpf_mem_cgroup_vm_events() -> memcg_events() -> memcg_events_index() > > And memcg_events_index() does: > > return mem_cgroup_events_index[idx]; > > where mem_cgroup_events_index is an array of size NR_VM_EVENT_ITEMS. If a > BPF program passes event >= NR_VM_EVENT_ITEMS, this would be an > out-of-bounds array read. > > The sister function bpf_mem_cgroup_page_state() below validates its idx > parameter before calling its callee: It's a false positive: the check is enforced by the bpf verifier based on type information. > >> +/** >> + * bpf_mem_cgroup_page_state - Read memory cgroup's page state counter >> + * @memcg: memory cgroup >> + * @idx: counter idx >> + * >> + * Allows to read memory cgroup statistics. The output is in bytes. >> + */ >> +__bpf_kfunc unsigned long bpf_mem_cgroup_page_state(struct mem_cgroup *memcg, int idx) >> +{ >> + if (idx < 0 || idx >= MEMCG_NR_STAT) >> + return (unsigned long)-1; >> + >> + return memcg_page_state_output(memcg, idx); >> +} > > Should bpf_mem_cgroup_vm_events() have a similar bounds check, perhaps: > > if (event >= NR_VM_EVENT_ITEMS) > return (unsigned long)-1; > > before calling memcg_events()? No. Here is required because idx is a simple int.