From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-170.mta1.migadu.com (out-170.mta1.migadu.com [95.215.58.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B4FAE286881 for ; Sun, 26 Oct 2025 15:40:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.170 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761493244; cv=none; b=I7TJY2aCO6oW7IR3mQrKi3cQtMLLBogFmWsyR4e46qyF8U1Kq3+ZLpu5CIxPRIlBgpI55pUzYG2DpgzeK0Tw998SdHOUXWMOByXXbdMfmVfszNSsWOgvKwhLM277VLuFNTvBrckBZ8ALjrGx0EocLR8wjr09/zbakTlGR1jWlmo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761493244; c=relaxed/simple; bh=dz1M6D9fsk5u2D1NH7RozLbg+MvXKtepO3skZdzY9DY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=m71SYxnhwsICF6ujc+sbX0E4dx+sUFU5sf3IBuJ2Do1sBu1JxiDXD3qgjGziEke/xKx2YfXweosr1A3ujrmqksYwaQU4+x9ven4N5FIjthyQ0sVXspsA18R+nUbKlVX9jU0kwxERNNqAvlnn+4AkaVtPNPO87s8fDHCXsgtoOMQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=X16MDmJh; arc=none smtp.client-ip=95.215.58.170 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) header.d=linux.dev header.i=@linux.dev header.b="X16MDmJh" 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=1761493230; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=c6h+Zn8ht8TyNdWjST5iIEW7Oxjr35Bqx9NXKCm8Gug=; b=X16MDmJhjzpdi6/Zk+mfSjg4LL3NXcNKW4LAV6yDC7W05vkpJ6gVk9IF6TYG2arsnUyGNL Tdam8AKfLYQkzZBnZPujpurJz4OM+yG3xguInHqoZITbLlmELbZaLNARWM8fHD7/Smpnah 4AdudzoM/yMcrUWwBzxMHjRzBsSZrtg= From: Leon Hwang To: bpf@vger.kernel.org Cc: ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, memxor@gmail.com, linux-kernel@vger.kernel.org, kernel-patches-bot@fb.com, Leon Hwang Subject: [PATCH bpf v3 0/4] bpf: Free special fields when update hash and local storage maps Date: Sun, 26 Oct 2025 23:39:56 +0800 Message-ID: <20251026154000.34151-1-leon.hwang@linux.dev> 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-Migadu-Flow: FLOW_OUT In the discussion thread "[PATCH bpf-next v9 0/7] bpf: Introduce BPF_F_CPU and BPF_F_ALL_CPUS flags for percpu maps"[1], it was pointed out that missing calls to bpf_obj_free_fields() could lead to memory leaks. A selftest was added to confirm that this is indeed a real issue - the refcount of BPF_KPTR_REF field is not decremented when bpf_obj_free_fields() is missing after copy_map_value[,_long](). Further inspection of copy_map_value[,_long]() call sites revealed two locations affected by this issue: 1. pcpu_copy_value() 2. htab_map_update_elem() when used with BPF_F_LOCK Similar cases happen when update local storage maps. This series fixes the issues by properly calling bpf_obj_free_fields() (or check_and_free_fields()) after copy_map_value[,_long]() and adds selftests to verify the fix. Changes: v2 -> v3: * Free special fields when update local storage maps without BPF_F_LOCK. * Add test to verify decrementing refcount when update cgroup local storage maps without BPF_F_LOCK. * Address review from AI bot: * Slow path with BPF_F_LOCK (around line 642-646) in 'bpf_local_storage.c'. * https://lore.kernel.org/bpf/20251020164608.20536-1-leon.hwang@linux.dev/ v1 -> v2: * Add test to verify decrementing refcount when update cgroup local storage maps with BPF_F_LOCK. * Address review from AI bot: * Fast path without bucket lock (around line 610) in 'bpf_local_storage.c'. * https://lore.kernel.org/bpf/20251016145801.47552-1-leon.hwang@linux.dev/ Leon Hwang (4): bpf: Free special fields when update [lru_,]percpu_hash maps bpf: Free special fields when update hash maps with BPF_F_LOCK bpf: Free special fields when update local storage maps selftests/bpf: Add tests to verify freeing the special fields when update hash and local storage maps kernel/bpf/bpf_local_storage.c | 3 + kernel/bpf/hashtab.c | 4 + .../bpf/prog_tests/refcounted_kptr.c | 178 +++++++++++++++++- .../selftests/bpf/progs/refcounted_kptr.c | 160 ++++++++++++++++ 4 files changed, 344 insertions(+), 1 deletion(-) -- 2.51.0