From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-182.mta1.migadu.com (out-182.mta1.migadu.com [95.215.58.182]) (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 5BD0F36337A for ; Thu, 30 Oct 2025 15:25:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761837931; cv=none; b=JXoc2tTjOiJGt6/RAI3YJ2rLNbeha4X4LTHZLCWizEiQ1YJ3/zE82+WkQ3m7UnWtRpwVsdNf9I5OWealrlTMBUSiNho8MV6GY4B0HD0Q2gFl9ayOaKrRBEeK2hxqG1Ay5EIrs4CekAJPo+4W37x6SkJvA52oa4JxfA28z3WSquo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761837931; c=relaxed/simple; bh=Me7vbqKDPfCUEl9uOwEbXFhN7y1z8OPplh80PGtMN9Q=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=ethce7DrAcHPEc70QCUduj/hkHX/TvdomsN3tBh3CYVFcXUQm0Fe6dS8ctkzaeBx4vvMz04TBql7WXKUrZUZ1lb3ZJ0AZNoneYJ5Eq/SA8kiqhG5AyWSMn5EoVaH1KjzCiziwcHD9BenQ3ZxnfiQZuhoX4quSXtAZxux+7MzE4c= 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=huPOTtWk; arc=none smtp.client-ip=95.215.58.182 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="huPOTtWk" 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=1761837927; 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=ZN3VhvADL3RotNT5kk7tKn1b8A+dl8RVEWaMrQxD5DE=; b=huPOTtWkq//K7tz8xCxSy8W0UcxxGNLpgyOQ/ZNeadOXKk0t+cQrLaKt2oo46+KVlKBmg7 yBI3lEWEBtfCqfvZ8LkLtwtP3n52/sZqg5M//m+/GLcb8jRFXv5pkEqwbnkRKFk4G/FHAC 5hIDfB+MbfhsXjvIOU8k7QY1IGKY7Ms= 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, ameryhung@gmail.com, linux-kernel@vger.kernel.org, kernel-patches-bot@fb.com, Leon Hwang Subject: [PATCH bpf-next v4 0/4] bpf: Free special fields when update hash and local storage maps Date: Thu, 30 Oct 2025 23:24:47 +0800 Message-ID: <20251030152451.62778-1-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 case happens when update local storage maps with BPF_F_LOCK. 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: v3 -> v4: * Target bpf-next tree. * Address comments from Amery: * Drop 'bpf_obj_free_fields()' in the path of updating local storage maps without BPF_F_LOCK. * Drop the corresponding self test. * Respin the other test of local storage maps using syscall BPF programs. 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 with BPF_F_LOCK selftests/bpf: Add tests to verify freeing the special fields when update hash and local storage maps kernel/bpf/bpf_local_storage.c | 2 + kernel/bpf/hashtab.c | 4 + .../bpf/prog_tests/refcounted_kptr.c | 134 +++++++++++++++++- .../selftests/bpf/progs/refcounted_kptr.c | 129 +++++++++++++++++ 4 files changed, 268 insertions(+), 1 deletion(-) -- 2.51.1