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 4C269138481; Sun, 24 Mar 2024 23:06:27 +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=1711321588; cv=none; b=gzlf89fbCFDrA0Gt8MP8wEPANn1t5wBrGvU+kDlzH6RSyPrJMW8nru4zjXiLVFPzIWLxq0ZsMhbZAJVtnbtJMKHxqJXEU0RwijIwrc1LJzN8R+VgZpVWYzwBBon25Clo1V1Bmx3y3PYTJbgD0gG3ImUvy3eAy3AJi5vZTliam4U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711321588; c=relaxed/simple; bh=BSB4jCWJU4ghse22gPst7g6+o8OVQyN+w/jFKOUHFEg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=NYyetcPkcnN4Zfz3H94GW0JnBD5M3MB18871FZF3YIo7fVLS7iRtYdyz13YUTSMXxOS4m4vVPB5OAbWjEyE03ncp/RWlGjrpdANwxiRPF89lROyuqOhgRtXd/CqXFxVca8HQghPBiwxQqXwXWnKrnDhRPp7hck9JHgXuhG1eiEg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Qa42jo1/; 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="Qa42jo1/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8EC5EC433C7; Sun, 24 Mar 2024 23:06:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1711321587; bh=BSB4jCWJU4ghse22gPst7g6+o8OVQyN+w/jFKOUHFEg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Qa42jo1/dEZdNZ0lvWQqgTdoSVUWrmpjn0LPXbuRgcOnKAPNqbfxM7jAMGD/a3EV+ pkHiodm8QPqN0+MMucQsxj7lDsssydj7Gfw7PE2iGpX/7Df9InXkqHl1nTdQ3Xi48x eTTjGZHF2vF+5if2Zn+l1S16Zy79fuY31hpG9IZlvvj3AM2x1Vhm9lGDeKIVQZr1j2 K5aBs+wtS7SHfa3txR71WElQtJQQHLY5tZ2fnFFe1bZVyyr09HRDiQ5CCn6uT4EHft Yxk1kajQha0WXe8ek4XvsEKtOcQZuiKrmU2bS8fJbbsyBnyM7l1L+yXE/7d99H3xEa VgVxReSwdTjMQ== 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 6.6 317/638] bpf: Fix hashtab overflow check on 32-bit arches Date: Sun, 24 Mar 2024 18:55:54 -0400 Message-ID: <20240324230116.1348576-318-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240324230116.1348576-1-sashal@kernel.org> References: <20240324230116.1348576-1-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 5b9146fa825fd..85cd17ca38290 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -498,7 +498,13 @@ 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) + @@ -508,10 +514,8 @@ 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