From nobody Mon Jun 8 05:24:50 2026 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 15BFB346AF8 for ; Fri, 5 Jun 2026 15:53:45 +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=1780674826; cv=none; b=tj2o/ps89Jn7SyW8YH0sz72eGFxL8mBGJAOU7Dm5E+JBoFOX4WUzapp6WDioTJBnzQXgBTVcRt6cm5CBIWjLRNMbJd/3uBNbjWpjkdca39I/UvN189+pIZlMQmZJ4xBL4Mw1lVCXDS14FkNq7BKYoWET0Lo5cyQH7NtApnAqafg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780674826; c=relaxed/simple; bh=/eRNs/ogIIaKVyWyFlMBj4uvfykEa3kuZQ9piENK1HY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Y2RwmDwfv9G3aRxgnWMkTH3QgrH9y/8WtjaGM7KRPfDQj0jVNkE0DRp9HMz+CJ2loTGPqHZ1U59jubUHdO46rzCUi16hp3tT1eUJ/6X3NLqyUun9wRIOPrV92AXkBS9FnVJBVbiZkKRasKUHe2j5D2cdeIc7YcIjrQvGClm2jPk= 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=FUelMOxN; 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="FUelMOxN" 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=1780674823; 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=ejoApRDr1nYqC2TLGz3CjwySzcrXPnhgjJK5sQw/7I4=; b=FUelMOxNDA3Vxtz4qala2bE3P46Zz15ScWMTqktSjNIU8QCbS5bGc6M25DZl1p3M4RnpUg uyw9gRHcMNJnqLK1nZEzq4+JWmHc6f+ME0dEPF3EasaVnjg+x9y983D5sMw+IVXXpbC70V wD/Mj8D32JXhPQsyrmt0bYSaKpelZEA= 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 1/3] bpf: Check tail zero of bpf_map_info Date: Fri, 5 Jun 2026 23:52:47 +0800 Message-ID: <20260605155249.20772-2-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: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" Since there're 4 bytes padding at the end of struct bpf_map_info, they won't be checked by bpf_check_uarg_tail_zero(). pahole -C bpf_map_info ./vmlinux struct bpf_map_info { ... __u64 hash __attribute__((__aligned__(8))); /* 88 = 8 */ __u32 hash_size; /* 96 4 */ /* size: 104, cachelines: 2, members: 18 */ /* padding: 4 */ /* forced alignments: 1 */ /* 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_map_info, hash_size). And, add "__u32 :32" to the tail of struct bpf_map_info. [1] https://lore.kernel.org/bpf/20260513224823.6494FC19425@smtp.kernel.org/ Fixes: ea2e6467ac36 ("bpf: Return hashes of maps in BPF_OBJ_GET_INFO_BY_FD") 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 bed9b1b4d5ef..e1730f449d9e 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -6733,6 +6733,7 @@ struct bpf_map_info { __u64 map_extra; __aligned_u64 hash; __u32 hash_size; + __u32 :32; } __attribute__((aligned(8))); =20 struct bpf_btf_info { diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 31a3b70a0b5d..89f020a44fc9 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -5406,10 +5406,11 @@ static int bpf_map_get_info_by_fd(struct file *file, { struct bpf_map_info __user *uinfo =3D u64_to_user_ptr(attr->info.info); struct bpf_map_info info; - u32 info_len =3D attr->info.info_len; + u32 info_len =3D attr->info.info_len, len; int err; =20 - err =3D bpf_check_uarg_tail_zero(USER_BPFPTR(uinfo), sizeof(info), info_l= en); + len =3D offsetofend(struct bpf_map_info, hash_size); + err =3D bpf_check_uarg_tail_zero(USER_BPFPTR(uinfo), len, info_len); if (err) return err; info_len =3D min_t(u32, sizeof(info), info_len); diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 7d0b282ba674..7caf667e86fe 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -6733,6 +6733,7 @@ struct bpf_map_info { __u64 map_extra; __aligned_u64 hash; __u32 hash_size; + __u32 :32; } __attribute__((aligned(8))); =20 struct bpf_btf_info { --=20 2.54.0 From nobody Mon Jun 8 05:24:50 2026 Received: from out-188.mta1.migadu.com (out-188.mta1.migadu.com [95.215.58.188]) (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 06E103C3428 for ; Fri, 5 Jun 2026 15:53:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.188 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780674832; cv=none; b=OniE17EyvaqsXsyOQUF4H9UouczOdf1gR/ELndHcjj/DdK2Ejv3N8ksLaUmRC8BUrpTBq9r5fiiHMP5xIKSepR7HVI6GLHcy40VJ8FnpGhdaB9KJAFOzxqDAo15OG4H98aQSriGHQqerRSitVsQoHLKi4REW/Rp699UnTYH/u8A= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780674832; c=relaxed/simple; bh=N0NMDwecXTGo3+B3JAWMygZw1UUZ6OzfQiT7QBgnI/A=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=UExYIp8PunfFV4RUVuEXA9KLLFKSYOJ75meu/feAqbUNKwXeIibdmgWUA3R3pzJ/vtMtGIqtGEalhhm0CfVrI/4hPh/9q3RNq+z8zzN2YCwSFoSUjnyuN7FsS/BlKyk24yYk8pcFfXs8rq+fXTzwUvSNqqw/66jDILFV8Wy3MJ4= 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=95.215.58.188 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: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" 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))); =20 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 *fil= e, u32 info_len =3D attr->info.info_len; struct bpf_prog_kstats stats; char __user *uinsns; - u32 ulen; + u32 ulen, len; int err; =20 - err =3D bpf_check_uarg_tail_zero(USER_BPFPTR(uinfo), sizeof(info), info_l= en); + len =3D offsetofend(struct bpf_prog_info, attach_btf_id); + err =3D bpf_check_uarg_tail_zero(USER_BPFPTR(uinfo), len, info_len); if (err) return err; info_len =3D 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))); =20 struct bpf_map_info { --=20 2.54.0 From nobody Mon Jun 8 05:24:50 2026 Received: from out-187.mta1.migadu.com (out-187.mta1.migadu.com [95.215.58.187]) (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 70E783E5A05 for ; Fri, 5 Jun 2026 15:53:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.187 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780674840; cv=none; b=uJ+mE2qTDZswIe3hXqGA5YMnGd0kNG8h/W92eSI9jpSsj8dwVtAfPsStFmk3npkZtZLuHGWFbF44BYc/13VuqevNgIYSn45EMB77H+XD6/IBePQOYvuzBqjp1u57MAdUFz9S1Eb9m3vtTnU2V2OdJtlqZL/Ydtte48g+WJnA7jc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780674840; c=relaxed/simple; bh=EgYgMVfqv6njLLBjyrAbnScrviM62jNC88o3hzWGWuE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=huksMP5NI06muiCOqNQjZ32Ar/Zq4qPpt8YjC0v1HFn03OevbM5mwpSEV66AfZbiQSL0oKfmSQ9i+8BX436P4ApZNFfNunHhxB0U/d20o6e+19SDQJChC5qV6bfkT3tRxOBEmmFsa4XC/VoRpRq3SlsOqLh6juu64yefUIQzFNA= 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=gyJBNUXm; arc=none smtp.client-ip=95.215.58.187 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="gyJBNUXm" 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=1780674835; 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=N4OrGRrkkmGvIx1F20YwZyuqT7Zri8Jmo/WTZI/HFMg=; b=gyJBNUXmseUQEgeOMEyh0cqqJZwbbyG8qEFRawMRfQ97CXO4OR6htkAVCNSm8N96H9g81X 2cRrZPZYE6BTyxJ+9UhOyMn6SHeug2Z94Z07odNxuPD9fqEq5IDDAQD+Lb8vEeWF0w11UO x3d+0Ug2T8qaSOfpHnuU88brIWatRm0= 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 Subject: [PATCH bpf-next v3 3/3] selftests/bpf: Add tests to verify checking padding bytes for bpf_[map,prog]_info Date: Fri, 5 Jun 2026 23:52:49 +0800 Message-ID: <20260605155249.20772-4-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: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" Add two tests to verify that the tail padding 4 bytes of struct bpf_map_info and bpf_prog_info are checked in syscall.c using bpf_check_uarg_tail_zero(). Signed-off-by: Leon Hwang --- .../selftests/bpf/prog_tests/bpf_attr_size.c | 55 +++++++++++++++++++ 1 file changed, 55 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_attr_size.c b/tools= /testing/selftests/bpf/prog_tests/bpf_attr_size.c index 32159dc64da8..87842c4347a6 100644 --- a/tools/testing/selftests/bpf/prog_tests/bpf_attr_size.c +++ b/tools/testing/selftests/bpf/prog_tests/bpf_attr_size.c @@ -62,8 +62,63 @@ static void test_query_size_boundaries(void) cgroup_skb_direct_packet_access__destroy(skel); } =20 +static void test_map_info_tail_zero(void) +{ + LIBBPF_OPTS(bpf_map_create_opts, map_opts); + struct bpf_map_info_fake { + __u8 info[offsetofend(struct bpf_map_info, hash_size)]; + __u32 pad; + } info =3D { + .pad =3D 1, + }; + int map_fd, err; + __u32 info_len; + + map_fd =3D bpf_map_create(BPF_MAP_TYPE_ARRAY, "arr", sizeof(int), 1, 1, &= map_opts); + if (!ASSERT_GE(map_fd, 0, "bpf_map_create")) + return; + + info_len =3D sizeof(info); + err =3D bpf_obj_get_info_by_fd(map_fd, &info, &info_len); + ASSERT_EQ(err, -E2BIG, "bpf_obj_get_info_by_fd"); + + close(map_fd); +} + +static void test_prog_info_tail_zero(void) +{ + LIBBPF_OPTS(bpf_prog_load_opts, prog_opts); + struct bpf_insn insns[] =3D { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + struct bpf_prog_info_fake { + __u8 info[offsetofend(struct bpf_prog_info, attach_btf_id)]; + __u32 pad; + } info =3D { + .pad =3D 1, + }; + int prog_fd, err; + __u32 info_len; + + prog_fd =3D bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, "test_prog", "GPL"= , insns, + ARRAY_SIZE(insns), &prog_opts); + if (!ASSERT_GE(prog_fd, 0, "bpf_prog_load")) + return; + + info_len =3D sizeof(info); + err =3D bpf_obj_get_info_by_fd(prog_fd, &info, &info_len); + ASSERT_EQ(err, -E2BIG, "bpf_obj_get_info_by_fd"); + + close(prog_fd); +} + void test_bpf_attr_size(void) { if (test__start_subtest("query_size_boundaries")) test_query_size_boundaries(); + if (test__start_subtest("map_info_tail_zero")) + test_map_info_tail_zero(); + if (test__start_subtest("prog_info_tail_zero")) + test_prog_info_tail_zero(); } --=20 2.54.0