From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-183.mta1.migadu.com (out-183.mta1.migadu.com [95.215.58.183]) (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 A6FC439B484 for ; Wed, 3 Jun 2026 14:45:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.183 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780497960; cv=none; b=YOFO/TjfjeRPsdx+DzzA+H0ddG0RJ0yFv2B3kQmJ7JQVMaZq3ZGgQGIs2s0550/jbbhLVA34G6OovsphaBMZybGOG9gk2Em0Yu2RWx6JhRA0Mo+BUvq+MGaJHBskheu26YxziyD/BoCyYlTz4ziclE733Scr3YFUknHd9/I1wOo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780497960; c=relaxed/simple; bh=lanIngwVKBH4hfpq3Gd0O0Q9cbbIVVMmvDoxT46E1fI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ISCYvOw9y53kBgoL+FY3eDD5JWQYCRMVn4bPDfMWvaIK35RHcNiYa+CHjDiw4CX+6c38frd0sBCajbq0WSy7PKmp83Lv0+oyOXN299nFwBNxTOrTsFKA1qmLtKYUJrKju3u594bbRCyALnpxO20ri+iiy14pfyehJYFtXsE6PFs= 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=WkS281h1; arc=none smtp.client-ip=95.215.58.183 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="WkS281h1" 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=1780497956; 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: in-reply-to:in-reply-to:references:references; bh=HfyZlUVAEYpdtuEgj/NlQqsjQF2GiYUHsCUEGQ1PtSg=; b=WkS281h1+Coh7LgqSo60D0I1ze9dkQbPt7l4XkLWlHHZFay9bZES8ibnFn9WLi87z3hWa7 Bee9g791mbylc+VwNTrzvBHwu692PP079n/WeXNq+BlNpQ+jOumB/NGjRCcjkInWj2DkZU mSU1VKO7N8mHqL2xRAsZEnSobaomJaA= From: Leon Hwang To: 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 , Leon Hwang , KP Singh , Stanislav Fomichev , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-patches-bot@fb.com Subject: [PATCH bpf-next 2/3] bpf: Check tail zero of bpf_prog_info Date: Wed, 3 Jun 2026 22:45:17 +0800 Message-ID: <20260603144518.67065-3-leon.hwang@linux.dev> In-Reply-To: <20260603144518.67065-1-leon.hwang@linux.dev> References: <20260603144518.67065-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT 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 --- 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); -- 2.54.0