From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-174.mta1.migadu.com (out-174.mta1.migadu.com [95.215.58.174]) (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 0E5623C819A for ; Fri, 5 Jun 2026 15:53:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780674833; cv=none; b=FUnt4K1Nbe3zQHNT3nBif+EiUj1swp0u3bgOS2eBDT6SJK+4u0jGSFLlklbFHw2OX/sbrfIWlVB/sGYz1r6Dp1635jEGxqWLKfVHXEo1r01J7Mg26WKnbbgnFyYg3XJ1Exno3RHY2uiLr3046xtv/LSRdph+u5fHOT8giThnhVU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780674833; c=relaxed/simple; bh=N0NMDwecXTGo3+B3JAWMygZw1UUZ6OzfQiT7QBgnI/A=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DYtjSKLR66BJT25CBr5Vn20+WTT3OSKEfM8lt+7frQ0EXlSil7rzeozBZIytmY1T4XNMdGfNHUC/xN9PZkGi+/74Pwz7wd+I2C/EzIrnAQeDcaebZwKOhW9Dn75SntfVsw/FduG0M2qhn2CubxRUZdb+JJuMJJdHlUh+SlyYpBw= 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=giQ78XHB; arc=none smtp.client-ip=95.215.58.174 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="giQ78XHB" 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=1780674829; 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=3I6KeKxzOta1ZBR0diw6dlq8OqECf/tpenQwEpWvgGA=; b=giQ78XHBqdY2ysvCvU8KP2UKHp5mx9wwOlaWRJjHM9dcEjaO5191kRaX+AjkstCzH++LC4 Dld6XidknHaEsLBPNxRAXBg4WGCJ1U4t/T388cZEl71APBdNPeiP+IiFgferva35XS6a81 ON6IJzvHA/UUyc+SrDTlfwvZdZQcQeY= 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 , Dave Marchevsky , Stanislav Fomichev , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-patches-bot@fb.com, Mykyta Yatsenko Subject: [PATCH bpf-next v3 2/3] bpf: Check tail zero of bpf_prog_info Date: Fri, 5 Jun 2026 23:52:48 +0800 Message-ID: <20260605155249.20772-3-leon.hwang@linux.dev> In-Reply-To: <20260605155249.20772-1-leon.hwang@linux.dev> References: <20260605155249.20772-1-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). And, add "__u32 :32" to the tail of struct bpf_prog_info. [1] https://lore.kernel.org/bpf/20260513224823.6494FC19425@smtp.kernel.org/ Fixes: aba64c7da983 ("bpf: Add verified_insns to bpf_prog_info and fdinfo") Acked-by: Mykyta Yatsenko Signed-off-by: Leon Hwang --- include/uapi/linux/bpf.h | 1 + kernel/bpf/syscall.c | 5 +++-- tools/include/uapi/linux/bpf.h | 1 + 3 files changed, 5 insertions(+), 2 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index e1730f449d9e..d5238df5e5eb 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -6712,6 +6712,7 @@ struct bpf_prog_info { __u32 verified_insns; __u32 attach_btf_obj_id; __u32 attach_btf_id; + __u32 :32; } __attribute__((aligned(8))); struct bpf_map_info { diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 89f020a44fc9..c5d4ae957e87 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -5121,10 +5121,11 @@ 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); diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 7caf667e86fe..3829db087449 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -6712,6 +6712,7 @@ struct bpf_prog_info { __u32 verified_insns; __u32 attach_btf_obj_id; __u32 attach_btf_id; + __u32 :32; } __attribute__((aligned(8))); struct bpf_map_info { -- 2.54.0