From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [117.135.210.5]) (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 D83333A5447; Thu, 9 Apr 2026 10:26:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=117.135.210.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775730371; cv=none; b=cmvENhWuUtYXivAZ5iVVeY0/Wmk0ThzhmDigP8yVzZc1QQqBucLLFDMHGuzcHBTB8VdZ2GK6JgyscQ2Z5g7eieNHP02gbfRR6wPNDk6BB1GahMmvuKgGMp4ywUnIYo3l5zKvAnwJ3MvagwdUW+Hp6FpSX1TOnZA2y7t3Pf7KdB0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775730371; c=relaxed/simple; bh=7py9+jmGAJ42gklg146TwBoQ25+pE+fdXjulq709fJc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=U0kHVDJTTQ77w6lZdUnW03fUvhdJYI0QwApqWMHDZSG6/wN/a+sdEm1IVPC1Hm8x88gMo2LfwAfLleMiFddGsFR7m6fhsaOgEStsp2SeD5cUyfJwnMmK66tD8a9bCn7Np2j+6RYUqNDr4M3WCIWtJcfQFzg84XqqBN5vyCk2/xs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=PNN0hgq2; arc=none smtp.client-ip=117.135.210.5 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="PNN0hgq2" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=oX ak1Wf+tJCIBtTfH/i2OKO0EooehvNI969H+oz08rc=; b=PNN0hgq2zZ/JWVvQHB wakqazxGzzbOiJZmpJ+BGhwF3nSh3uvjD8Fp0nJbpcpYu7H/+owzBXh90+WZc+Dd 63CSCfO7//XCKhgbr/gK7d5R6yX7bwwBeNMEA8Ro/Xwc8yM7nmcL4sjIn85f2vtg 9KowFUKUg13GOOTaGsf+SjU/Y= Received: from localhost.localdomain (unknown []) by gzga-smtp-mtada-g0-1 (Coremail) with SMTP id _____wD3H_WOftdpMHcLEA--.37469S2; Thu, 09 Apr 2026 18:25:19 +0800 (CST) From: Feng Yang To: jiayuan.chen@linux.dev Cc: andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, john.fastabend@gmail.com, jolsa@kernel.org, kpsingh@kernel.org, linux-kernel@vger.kernel.org, martin.lau@linux.dev, mattbobrowski@google.com, memxor@gmail.com, song@kernel.org, yangfeng59949@163.com, yonghong.song@linux.dev Subject: Re: [PATCH bpf] bpf: Fix Null-Pointer Dereference in kernel_clone() via BPF fmod_ret on security_task_alloc Date: Thu, 9 Apr 2026 18:25:18 +0800 Message-Id: <20260409102518.258752-1-yangfeng59949@163.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <409f3694-a054-4288-acd9-7900cc8f8620@linux.dev> References: <409f3694-a054-4288-acd9-7900cc8f8620@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-CM-TRANSID:_____wD3H_WOftdpMHcLEA--.37469S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7ZF18CFWxGF4kGr45Cr17Wrg_yoW8XF1rpF 4fKF9rJF1vyFW29ryIyF47uayFqa4Dtay3WFZYk347AFsYqrn5JF4UGFyj9rW3CrWDAr18 ta12vanIya1DZFDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0JjjKZXUUUUU= X-CM-SenderInfo: p1dqww5hqjkmqzuzqiywtou0bp/xtbC0A8Ti2nXfo-7uQAA3K On Wed, 8 Apr 2026 20:16:45 +0800 Jiayuan Chen wrote: [...] > > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > > index 594260c1f382..3bfc67983e12 100644 > > --- a/kernel/bpf/verifier.c > > +++ b/kernel/bpf/verifier.c > > @@ -18413,8 +18413,10 @@ static bool return_retval_range(struct bpf_verifier_env *env, struct bpf_retval_ > > *range = retval_range(0, 0); > > break; > > case BPF_TRACE_RAW_TP: > > - case BPF_MODIFY_RETURN: > > return false; > > + case BPF_MODIFY_RETURN: > > + bpf_security_get_retval_range(env->prog, range); > > + break; > > This is a breaking change. The verifier rejection log should be more > descriptive > so users can understand why their program is being rejected. It should be easy to see from the existing error log that the return value does not meet the requirements: At program exit the register R0 has smin=1 smax=1 should have been in [-4095, 0] processed 2 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0 > > > case BPF_TRACE_ITER: > > default: > > break; > > Also, I think a whitelist approach would be better here. > The known danger is specifically those security hooks whose return > values get fed into ERR_PTR() by callers, such as: > - security_task_alloc > - security_inode_readlink > - security_task_movememory > - security_inode_follow_link > - security_fs_context_submount > - security_dentry_create_files_as > - security_perf_event_alloc > - security_inode_get_acl