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 169B317EB75; Sun, 24 Mar 2024 22:40:12 +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=1711320013; cv=none; b=ePWh+c4ggvHDW7h1/OYgHC8hA/rzqBQ1DwRQowyErwt6Mq5kq+7cLebbTeBFQoGiWcYrpqKRtvU85keHxsbogIVG7z4SUpvqjIw19BZ+FTFr5j6VJMU5RvA/GtIBTT551GWuX71liFMxz1VoGvgHmSr2FU8bwnIqAuOIk9wHkIM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711320013; c=relaxed/simple; bh=VIbvBBzSO6jB4GlKBMOGSPLMt75A1XyStIcCo4tKvWg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=UweUgPQebyXGQoBHAWWEPpgfHP2WgbUJKQdLJv+3YORT9BLd0iVdPYf1El0o66ZxzURxmbGtV3ar8ru3ICM9iQk+QUjHIEqboqOETq0G6IjFzPbIsiJq5i506GYJgbtWM1oiC6/UUzqORaR7oCKYnFa7I2h54zoffD5KY+Z6juA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GKq+934i; 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="GKq+934i" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E656BC433C7; Sun, 24 Mar 2024 22:40:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1711320012; bh=VIbvBBzSO6jB4GlKBMOGSPLMt75A1XyStIcCo4tKvWg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GKq+934i3IiQ0A8J9tY9mOkG5pnV0jxgxj7gMetSaaLUm+x5Be7BalSbO5w1szUwy GOSlr9vPC5OA6doJItwcjG0omRN5ZjehgQyOYOw2SRsXL8HONhs+HTckw09nW4uoZ4 Aq5hFL+yQjqbAxN/O5btp+BlS1GpML0haj8Pq7UugJoybbtqNS9OvpK1ctydQOcYPW XcJGphuoaSsKIzyGshkxRFiGDUTCMA21Ibo5ET2DquJ9pXa3VVhOrCYho+uoLkXC+S 7MvnRU6W0UaQxrkb210WHMaKypNd0S9WPsfo7Ilwng6LJMvpdjDIFNJsnQCXSZQHIh WRcBuRfRvcCQg== 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 6.8 320/715] bpf: Fix hashtab overflow check on 32-bit arches Date: Sun, 24 Mar 2024 18:28:19 -0400 Message-ID: <20240324223455.1342824-321-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240324223455.1342824-1-sashal@kernel.org> References: <20240324223455.1342824-1-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 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 Høiland-Jørgensen 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 03a6a2500b6ab..3a088a5349bc0 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -499,7 +499,13 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr) num_possible_cpus()); } - /* 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 = -E2BIG; + if (htab->map.max_entries > 1UL << 31) + goto free_htab; + htab->n_buckets = roundup_pow_of_two(htab->map.max_entries); htab->elem_size = sizeof(struct htab_elem) + @@ -509,10 +515,8 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr) else htab->elem_size += round_up(htab->map.value_size, 8); - err = -E2BIG; - /* prevent zero size kmalloc and check for u32 overflow */ - if (htab->n_buckets == 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; err = bpf_map_init_elem_count(&htab->map); -- 2.43.0