From nobody Mon Jun 8 08:28:02 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 1E040480320 for ; Wed, 3 Jun 2026 14:45:50 +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=1780497952; cv=none; b=qb2rBtYHqz2jDKPcKzwv46TpSfJLhwqQgXR+9yTrRwOQoE2DrOrpmLJUq11Ra2wPYdIdwQ86AT7c/oei19xEOnLnXB5y3oCLWHpt+1iH71z30bcbH2myEJTCYFPy0oS5zON1BG2ND1ixSP+/1LFOzfoIq/qjNrBsM089NITSJ20= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780497952; c=relaxed/simple; bh=qrblDqB4/8UTNvwsfuUvtB8MQ8mzMY7zUiDc+Mbzycs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hupyWLOkpHLASWN9xonE9uhi2cXryHag0L/LhKVCkpk5uLw7lzTduztdA4f2ElwravnkeCz834wQ816h/MtNdXcJ6K41WIy3vG54a2lCNKArnr7+rogEZLZCdg2QqiyFS1LqEvi1vY4TgJNaahMiwkzxU80B0TcTB95tELyp0Uk= 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=MQqEf4xo; 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="MQqEf4xo" 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=1780497949; 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=I8qiNtbqWgHQYGAUM0S9VH2blx8YU6TzskWNL0hFkek=; b=MQqEf4xoFIcpXEy97BWN13L2YnJq7b8UasO2tv25zetxF3l6LgsOWuKg4Gdxk81+1BNx9G DQNdhbZTe7nxBDJG6xZXtZZ17mmAHdA8yaAMFsHR0rKUuYOAinvrhvrgSy+QMq9jKuPIW6 jSgcqZC+f0TjB3mHeqY8UiAe0sIfBYc= 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 1/3] bpf: Check tail zero of bpf_map_info Date: Wed, 3 Jun 2026 22:45:16 +0800 Message-ID: <20260603144518.67065-2-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: 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). [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") 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 625a4366fe6d..1007fb7c87e9 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -5400,10 +5400,11 @@ 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); --=20 2.54.0 From nobody Mon Jun 8 08:28:02 2026 Received: from out-186.mta1.migadu.com (out-186.mta1.migadu.com [95.215.58.186]) (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 C1370481FDD for ; Wed, 3 Jun 2026 14:45:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.186 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780497960; cv=none; b=eknDFQbg8HVRPCItz5NDa8rwxHi4afYilw59Wg7G64oIimWTHZfqGYdgYOiV6BF4xwB4/7BvHu+ExDgax/MGueMl+RP1NQnMyiYjfF93kQ7JkFgPzvkrtmhSG0DUy1T5izEZVjUvvZgJGmNWVsAlLHcTrVhfaKSoKsx0Ws9r5SU= 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=95.215.58.186 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: 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). [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 *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); --=20 2.54.0 From nobody Mon Jun 8 08:28:02 2026 Received: from out-179.mta1.migadu.com (out-179.mta1.migadu.com [95.215.58.179]) (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 421293A3E67 for ; Wed, 3 Jun 2026 14:46:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.179 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780497967; cv=none; b=LXyyRh/3moRpFPIB7wdFBsIFkJyixdC5HnA7PvgydQSKZ+v2oIQfipHufqyTGlceeMjJC+WuyRi30gIIiNxnSeiEorJagqQQPwQXlhJVfqJD21+qJxDpp9QyIqShndLpuOCfQsyRsAfn4SZZmEWnSRotJWVhPXDO46mg0oFWAnk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780497967; c=relaxed/simple; bh=EgYgMVfqv6njLLBjyrAbnScrviM62jNC88o3hzWGWuE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=sls1zf0TQJH12urY/GKt/rHos4dPmKH/ZkUZ5uUEhXFevtHM5KogY59pG495asi5kmIz/zDwUmVljhjdsjmG79X18UfXH/rpmoSVDX/wGy+wuIB/sGPZ19KaFYpu4He54IOc1iI5rj2O4X8P9eXkILDJ038ZvTJb9Cx5yWz9riQ= 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=nYxWA2ff; arc=none smtp.client-ip=95.215.58.179 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="nYxWA2ff" 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=1780497964; 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=nYxWA2ffb/dRZPWfJpocqDBmb8sP/QmjdUY44EC7DDh+s15gsvdkEPa8w3iwnc/6axo26g H6znXxtyZq5U4H5xlIq48J+L1SfJxnBxnkwLDxe33uQk9Xbsnx5m320gOfXFxgd2tvYMlA TJvagTHRcpgSbgR+Bbulc74A0LsGhx4= 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 3/3] selftests/bpf: Add tests to verify checking padding bytes for bpf_[map,prog]_info Date: Wed, 3 Jun 2026 22:45:18 +0800 Message-ID: <20260603144518.67065-4-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: 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