From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f50.google.com (mail-wr1-f50.google.com [209.85.221.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 38C772264AB for ; Wed, 3 Jun 2026 15:17:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.50 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780499860; cv=none; b=pkDeqlkooyrIv88ozmUPw6J6UJNcdBNeqHtPWb818znQ4KSmH4hXmhMbd0MQmx3z0q/7RtfJoDYEIW8e9ukdIBFHlSAlC1FYBqnKHq2cXtgWg+ZMoYuRIPtZaGgYsdiqkl0W8Iq9CJiPI2jQPtZ4rknOsQlBJ+2nke7jUxcxX/I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780499860; c=relaxed/simple; bh=yKBQM/dYhJDWNF+XWCSKcsh0LWE/TAYU2zGm7ql6dk8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=fUvdLa+ghAGne11rvySWrRwsJXjik7oOkQIk86pQHoVoBzcfpuz0A0pbRsslzkfXbhuOTehMRxXF9BzadzfVaStOA8AlRuMwKB10/P2e0aHvAllUTBJYJTV/rGgiPUFRCUw8fWCwGRX7xLiZ3ZGM6RZ3DG21IsCqQFaVYKgkSoM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=PXVwvOeH; arc=none smtp.client-ip=209.85.221.50 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="PXVwvOeH" Received: by mail-wr1-f50.google.com with SMTP id ffacd0b85a97d-45ef372c58aso2913736f8f.0 for ; Wed, 03 Jun 2026 08:17:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1780499857; x=1781104657; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=hnkH5xFEJ6g6oqedeDPHM9btk1uLc+DnFLjyYvq9sR4=; b=PXVwvOeHCVsO8ZIndw/CBezw1mtKNimrhl3s9nxoxqr/czz2Nl116bwsGnoH+wLaTM kQMQbyG0fFmwhz5i6NNfKarEQiXRd8x/YqIrT8t9vygU3C80KmED/VRttMn2E1NtV496 j06JToVoDde3yllo03QPh/9hYUGTVdC/UJ+QYD37x3OiplBtsPKduaTI9m2SHaFhsJrs DuUlEAsf2gdlxZZl/yDhqD51aHmCyyb2IoP+CSuDGKBWPn7CWKVZwSlS1pTqNeNOxnXI sgTuctBp0ASHD9KBfxOBSUdACFL6bIbwtOcFYjN+XIvW6JfpIW+7POBCSK2ZxXoqE1/j r6pA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780499857; x=1781104657; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=hnkH5xFEJ6g6oqedeDPHM9btk1uLc+DnFLjyYvq9sR4=; b=YRS2jvTs+R7giG29dcgwwrpS/as1fFGWSG5ARhKcfpZVU7KSo9nDhZKjEv/fW38pBu 4tSSHxkqArphO+LYiFAvr32FRvotdtiT2rZ33UAVmYF2sCaREE5DF4WaJuL3VCV6CdtA 41ZnxB7bzVbW+GyeBpttXf/7yKyKBAn17vLsVA1qsTb7auCeh6oAwO3uiPGnpug13AW6 7FV4eSii8w4aLfP5lImnB5aa8QBqG5YwAkr2OZNfg2UzHg7dGDb24QD3gEjke+SiOgKz XItuSjcV5cIPDuP85jocyzMrVAn4FaGAdaTveG+62UuRkMDODeG6I3kNzcFbLZVQ1wPB Uv4Q== X-Forwarded-Encrypted: i=1; AFNElJ9zSxrOcjXlW32XCRB3+BaCo/33dFxWB7tNzX+gG2ZpvLRk6LlAp1rI3AngWB4yCneF2ObP+V4M7s2IXaA=@vger.kernel.org X-Gm-Message-State: AOJu0YyvByxrxL3ceJ7ojllC/VKCAMCfFNUbmvKsiI0rmUYCGXyDjJen 7yehyFPSaEt2s2GXDWEhFyJUHuviWEbX/cNA4bAYPKXZ0g16KYUURFKo X-Gm-Gg: Acq92OHgfwo0MKTk7lQQqTJ/STyeWOEifAi6lRU9/KkKYupfm2nfR1ah+5PR41raIrA AdIbzuSPnnefsrDUCTiU+QWwhL7REiDDBUad5ZsJ0CizjDdymwowfSVdHuGGp9qnAotBywwEUIp 0BSfyLBFj7kBYL4dBYYMnJwK48rDS9WGYP+3COEqFKG3wkA2h+zrbl3Xw6kETWe+qKgOIARFAzJ +7fjMiPLs0mThYEC6dsDSPSLaiyOgpZrXohCZ8PU/FZvPrXZRAXqtp3qGJDDdtVOTM4rXr3tMMZ yVQwkLnTm+DedkxwMtQgIYSC4vxCxMYnzuZa25sbnjKKB+ja/1ETIe/Y53U3dsBojxdy/uukzm8 fK0pPVrFb2848e1SxFkQIOKVLKKK6pAO+f2INWuNquzPPnIoa7UcRlwgq7ZyEOWpq0PuOVYCD9Z +J7060uYwlFOfnu1MA4orXrAPpgD3p2RXZJUcA8Psi0QdruiiyhNoQphXn8M7SCQieI88PDT1xJ CJI/GfxrxLezCXk4StKu84gSEOLx89G X-Received: by 2002:a5d:5989:0:b0:45e:e44b:313e with SMTP id ffacd0b85a97d-4602181fac2mr5917728f8f.19.1780499856561; Wed, 03 Jun 2026 08:17:36 -0700 (PDT) Received: from ?IPV6:2a01:4b00:bd1f:f500:f867:fc8a:5174:5755? ([2a01:4b00:bd1f:f500:f867:fc8a:5174:5755]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4601f0a43e9sm8398676f8f.0.2026.06.03.08.17.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 03 Jun 2026 08:17:36 -0700 (PDT) Message-ID: Date: Wed, 3 Jun 2026 16:17:35 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH bpf-next 2/3] bpf: Check tail zero of bpf_prog_info To: Leon Hwang , bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Kumar Kartikeya Dwivedi , Song Liu , Yonghong Song , Jiri Olsa , Shuah Khan , Yuyang Huang , KP Singh , Stanislav Fomichev , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-patches-bot@fb.com References: <20260603144518.67065-1-leon.hwang@linux.dev> <20260603144518.67065-3-leon.hwang@linux.dev> Content-Language: en-US From: Mykyta Yatsenko In-Reply-To: <20260603144518.67065-3-leon.hwang@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/3/26 3:45 PM, Leon Hwang wrote: > Since there're 4 bytes padding at the end of struct bpf_prog_info, they > won't be checked by bpf_check_uarg_tail_zero(). > > pahole -C bpf_prog_info ./vmlinux > struct bpf_prog_info { > ... > __u32 attach_btf_obj_id; /* 220 4 */ > __u32 attach_btf_id; /* 224 4 */ > > /* size: 232, cachelines: 4, members: 38 */ > /* sum members: 224 */ > /* sum bitfield members: 1 bits, bit holes: 1, sum bit holes: 31 bits */ > /* padding: 4 */ > /* forced alignments: 9 */ > /* last cacheline: 40 bytes */ > } __attribute__((__aligned__(8))); > > If a future kernel extension adds a new 4-byte field, older userspace > programs allocating this structure on the stack might inadvertently pass > uninitialized stack garbage into the new field, permanently breaking > backward compatibility. -- sashiko [1] > > Fix it by changing sizeof(info) to > offsetofend(struct bpf_prog_info, attach_btf_id). > > [1] https://lore.kernel.org/bpf/20260513224823.6494FC19425@smtp.kernel.org/ > > Fixes: b79c9fc9551b ("bpf: implement BPF_PROG_QUERY for BPF_LSM_CGROUP") > Signed-off-by: Leon Hwang > --- Acked-by: Mykyta Yatsenko > kernel/bpf/syscall.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > index 1007fb7c87e9..0c86a70d31c1 100644 > --- a/kernel/bpf/syscall.c > +++ b/kernel/bpf/syscall.c > @@ -5115,10 +5115,11 @@ static int bpf_prog_get_info_by_fd(struct file *file, > u32 info_len = attr->info.info_len; > struct bpf_prog_kstats stats; > char __user *uinsns; > - u32 ulen; > + u32 ulen, len; > int err; > > - err = bpf_check_uarg_tail_zero(USER_BPFPTR(uinfo), sizeof(info), info_len); > + len = offsetofend(struct bpf_prog_info, attach_btf_id); > + err = bpf_check_uarg_tail_zero(USER_BPFPTR(uinfo), len, info_len); > if (err) > return err; > info_len = min_t(u32, sizeof(info), info_len);