From mboxrd@z Thu Jan 1 00:00:00 1970 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 1952417B4E4; Sun, 24 Mar 2024 23:41:57 +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=1711323717; cv=none; b=VUOOiH8cPBKGDlIfQtw31bRHDtJ5ScAr8AN4QjMnTldZZbE4DDd7QbGo9nUszt9DgStN1QL4dPsth39P/qsVjyIWqFih8N1bBhoWzOoXG4DiWTBoD952mSX5R3BlH0op/LLaPwrY3b5YWOk0oPmwLnH7/RJ0R/yQJKAb4UudDiY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711323717; c=relaxed/simple; bh=UMvKY0wk5C7zCqIQwVCdsZgWyc39Rvq8mbRFlU1ZrN8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=BdbILkoS6Mkx0yaNGuhrQK4yS9qH2UXZ4zCyO1jatHYTlF1XJ1nGrX5M0Y9cJwu7TDaYEuUsd8Y9dF/Vl1//5wl/rDR9RW3gPIvuOj0jO8KFZLTY6Cd8qzykmivH487jdTZMBEstbnpw5guongTFjltAEVnGF6XGD7jGvpifyrU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ECprwjQg; 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="ECprwjQg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 408F6C43399; Sun, 24 Mar 2024 23:41:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1711323717; bh=UMvKY0wk5C7zCqIQwVCdsZgWyc39Rvq8mbRFlU1ZrN8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ECprwjQgfmnO/dv51l6VoFOEQyGgE7OA9lA5ybAfaKwOJCathq3HW6odfxcBll/9O +RCO4EKpxSWbRDPA04K2XzVvHPb9W/C1HpjGWOMZRitGYgJGscFXV3UvPPAxMQjCy2 S1sCo57vviTGE2zxCqltA3O4zFVYesTZLMoEAU8gDp6otLWokV45u1vI48jLQ0Mcv7 bSZDfxLlkztEFBwTRDed9zEbeY39oNwXcKY2XBtEZvrvtXwL6DB8B7uW9v90rKUR8F C3wpNuYUiyv6UrVaow2LtfsCmlqGQhP0nPiXBk/fB12NUI6yj+jMC3wvAQaevc98/E G8cf102Dt4EpQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , syzbot+8cd36f6b65f3cafd400a@syzkaller.appspotmail.com, Alexei Starovoitov , Sasha Levin Subject: [PATCH 5.10 090/238] bpf: Fix DEVMAP_HASH overflow check on 32-bit arches Date: Sun, 24 Mar 2024 19:37:58 -0400 Message-ID: <20240324234027.1354210-91-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240324234027.1354210-1-sashal@kernel.org> References: <20240324234027.1354210-1-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: 8bit From: Toke Høiland-Jørgensen [ Upstream commit 281d464a34f540de166cee74b723e97ac2515ec3 ] The devmap code allocates a number hash buckets equal to the next power of two of the max_entries value provided when creating the map. When rounding up to the next power of two, the 32-bit variable storing the number of buckets can overflow, and the code checks for overflow by checking if the truncated 32-bit value is equal to 0. However, on 32-bit arches the rounding up itself can overflow mid-way through, because it ends up doing a left-shift of 32 bits on an unsigned long value. If the size of an unsigned long is four bytes, this is undefined behaviour, so there is no guarantee that we'll end up with a nice and tidy 0-value at the end. Syzbot managed to turn this into a crash on arm32 by creating a DEVMAP_HASH with max_entries > 0x80000000 and then trying to update it. Fix this by moving the overflow check to before the rounding up operation. Fixes: 6f9d451ab1a3 ("xdp: Add devmap_hash map type for looking up devices by hashed index") Link: https://lore.kernel.org/r/000000000000ed666a0611af6818@google.com Reported-and-tested-by: syzbot+8cd36f6b65f3cafd400a@syzkaller.appspotmail.com Signed-off-by: Toke Høiland-Jørgensen Message-ID: <20240307120340.99577-2-toke@redhat.com> Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- kernel/bpf/devmap.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index ca2cade2871b8..07b5edb2c70f5 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -129,13 +129,14 @@ static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr) bpf_map_init_from_attr(&dtab->map, attr); if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) { - dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries); - - if (!dtab->n_buckets) /* Overflow check */ + /* hash table size must be power of 2; roundup_pow_of_two() can + * overflow into UB on 32-bit arches, so check that first + */ + if (dtab->map.max_entries > 1UL << 31) return -EINVAL; - } - if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) { + dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries); + dtab->dev_index_head = dev_map_create_hash(dtab->n_buckets, dtab->map.numa_node); if (!dtab->dev_index_head) -- 2.43.0