From nobody Fri Dec 19 20:13:58 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 65C83184314; Sun, 24 Mar 2024 23:51:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711324278; cv=none; b=fqPwWpv31r8ebvRju4UlMfxUOVvqA331U1RNbJZzB6o8XSFbXcVR9bI2/YOLrwUNZdQ0Oyp2J3yjbRF/8wns1HJDrri3a/sgbCRCCCyWAbbwlu5IxO3CXdpmHPcjnx1z8du5QAXNVP9i4I/lHplgnSozompa+sPliX5XEeFMVZM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711324278; c=relaxed/simple; bh=QnZwcPZGcyCW/XtB6zKt3HftXxpmW+ty+R0k8p/gbuM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=iLpKuaiMgQTWfbC1nm02MgDMD8G1s5d0rNdNXuUTgOUnT4wDKUPdU3j/XyH30GsB/A1s/jzJ/VS2itL8Q8YHeDPkcFRr0IGWhVlPF5+FsUrEsMm86emEsyohUyHMpeXv2Y1dezH2NRl2qd2uT/JD5/GBBnfJcGMm2cBZg/45sEA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lKAm6kJZ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="lKAm6kJZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 43EE6C433F1; Sun, 24 Mar 2024 23:51:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1711324277; bh=QnZwcPZGcyCW/XtB6zKt3HftXxpmW+ty+R0k8p/gbuM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lKAm6kJZG5o+Yrv12/rDm2rOu9NAK0xYYfrndCs53LrYPGEZMps7H9mddxVu+kIIg AkD/yTiQo6WjQiGoqWecuyKa3flzXQgz1VKUN9os35IVDcTbDlUuxlkvqWXEV/eu6m Tv8v/yws8cqvl11isxZHH6MUqK4sSCdxqLMY7WyPpltsemKnbb/F3HloIYx7diqcXT 8crc12GQIO9s9wiibgpk4lHgnyi9buf24MOv6QK/JKLY7m83ZjKNkgWShahGqvmC6u Nt1fk2hJJP98KkJKz3CUiGafFmsUToV1zplkv8hOvrfgRyYh/1OWQP8PwaZeamTpJE 1e6ukPWYFUL1w== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , Alexei Starovoitov , Sasha Levin Subject: [PATCH 4.19 055/148] bpf: Fix hashtab overflow check on 32-bit arches Date: Sun, 24 Mar 2024 19:48:39 -0400 Message-ID: <20240324235012.1356413-56-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240324235012.1356413-1-sashal@kernel.org> References: <20240324235012.1356413-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: quoted-printable From: Toke H=C3=B8iland-J=C3=B8rgensen [ Upstream commit 6787d916c2cf9850c97a0a3f73e08c43e7d973b1 ] The hashtab code relies on roundup_pow_of_two() to compute the number of hash buckets, and contains an overflow check by checking if the resulting value is 0. However, on 32-bit arches, the roundup code itself can overflow by doing a 32-bit left-shift of an unsigned long value, which is undefined behaviour, so it is not guaranteed to truncate neatly. This was triggered by syzbot on the DEVMAP_HASH type, which contains the same check, copied from the hashtab code. So apply the same fix to hashtab, by moving the overflow check to before the roundup. Fixes: daaf427c6ab3 ("bpf: fix arraymap NULL deref and missing overflow and= zero size checks") Signed-off-by: Toke H=C3=B8iland-J=C3=B8rgensen Message-ID: <20240307120340.99577-3-toke@redhat.com> Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- kernel/bpf/hashtab.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 8e379b667a0f7..16081d8384bfc 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -330,7 +330,13 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *= attr) num_possible_cpus()); } =20 - /* hash table size must be power of 2 */ + /* hash table size must be power of 2; roundup_pow_of_two() can overflow + * into UB on 32-bit arches, so check that first + */ + err =3D -E2BIG; + if (htab->map.max_entries > 1UL << 31) + goto free_htab; + htab->n_buckets =3D roundup_pow_of_two(htab->map.max_entries); =20 htab->elem_size =3D sizeof(struct htab_elem) + @@ -340,10 +346,8 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *= attr) else htab->elem_size +=3D round_up(htab->map.value_size, 8); =20 - err =3D -E2BIG; - /* prevent zero size kmalloc and check for u32 overflow */ - if (htab->n_buckets =3D=3D 0 || - htab->n_buckets > U32_MAX / sizeof(struct bucket)) + /* check for u32 overflow */ + if (htab->n_buckets > U32_MAX / sizeof(struct bucket)) goto free_htab; =20 cost =3D (u64) htab->n_buckets * sizeof(struct bucket) + --=20 2.43.0